The 25 Best Arrowverse Episodes Ranked

Never has any comic book TV franchise been as ambitious as the Arrowverse — the shared world of DC Comics superheroes on The CW that launched in 2012 with "Arrow." Two years later, "The Flash" debuted, and the Arrowverse later added spin-offs "Legends of Tomorrow," "Batwoman," "Supergirl," and "Black Lightning." 

An impressive and presently unmatched endeavor, the Arrowverse introduced audiences to a wealth of characters from DC Comics. In fact, it's been indisputably more successful than the DCEU in terms of scope — producing more epic, sprawling tales than any DC adaptation that's been on the big screen. The Arrowverse even adapted a number of iconic crossover events from the comics, which entail dozens of heroes teaming up to take down the galaxy's biggest threats.

A groundbreaking universe of stories, "The Arrowverse" has never been afraid to explore DC Comics' rich history, their diverse characters, and monumental storylines, with a unique mix of action, drama, humor, and heart. So suit up and prepare for adventure, because we're ranking the 25 best episodes in the entire Arrowverse.

During its brief and troubled run, "Batwoman" managed a few standout episodes, and the best of the bunch is the series' contribution to "Crisis on Infinite Earths," a multi-part story that spans five series in the franchise and beyond. A loose adaptation of the landmark company-wide crossover from 1985, the story does more than just bring together "Arrow," "The Flash," "Batwoman," "Supergirl," and "Legends of Tomorrow" – it also incorporates older movies and TV shows based on DC Comics.

The action picks up as the heroes are mourning the loss of Oliver Queen (Stephen Amell) but determined to end the threat posed by the cosmic despot called the Anti-Monitor (LaMonica Garrett). Now it's up to the remaining heroes to traverse the multiverse and track down the Paragons — seven legendary heroes said to be able to save all of reality. This means that we not only get Tom Welling returning as Clark Kent from "Smallville," but Kevin Conroy makes his first ever live-action appearance as Bruce Wayne after voicing him in animation for decades. Brandon Routh, meanwhile, pulled double duty as Ray Palmer, aka the Atom, and got the chance to reprise his role as the Man of Steel from 2006's "Superman Returns," squaring off against his successor, Tyler Hoechlin.

Full of jaw-dropping twists and turns, the episode is less an episode of "Batwoman" than it is an event story all its own and remains one of the best that the "Arrowverse" ever produced.

While "Black Lightning" never received quite the same amount of attention as flagship shows "Arrow" and "The Flash," it is a fine series in its own right that produced four seasons and nearly 60 episodes. Starring Cress Williams, the series introduces audiences to retired crime fighter Jefferson Pierce, who steps back into the streets to battle injustice. Confronting real world issues, "Black Lightning" is a different kind of series, and that's true of its structure, too — each season splits into a series of multi-episode arcs. The best entry in the series remains "Grab the Strap," the fourth part of the "Book of Markovia" story in Season 3.

The four-part story has Pierce struggling in the wake of the "Crisis on Infinite Earths" storyline and sees ex-wife Lynn (Christine Adams) becoming imprisoned in the highly controversial nation of Markovia. Scientists there believe that Lynn may be key to creating a cure for meta-humans, and in "Grab the Strap," Pierce and his team of allies must infiltrate a highly guarded compound to rescue her.

"Black Lightning" is the most underrated "Arrowverse" series and deserves recognition for its solid stories, powerful message, and strong performances. If you've never seen it, "The Book of Markovia" arc is its best.

When the DCEU was still in its earliest stages on the big screen and the crossover epic "Justice League" was still years away, the Arrowverse was making superhero team-ups a reality on television. In 2014, "Arrow" and "The Flash" crossed over for the first highly promoted two-part story. Part 1 of the crossover began on "The Flash," and the story's conclusion is the "Arrow" episode "The Brave and the Bold," named after the long-running DC Comics team-up title.

Though they'd met before when Barry Allen (Grant Gustin) was just a forensics expert with the Central City Police Department, the episode marks the first true team-up between Barry and Oliver Queen in their superhero identities. It begins with Oliver and allies Roy Harper (Colton Haynes) and John Diggle (David Ramsey) in pursuit of a mysterious villain. Pretty soon, they get unexpected help from the Scarlet Speedster himself, The Flash. Despite technically being the second part of a single story, "The Brave and the Bold" largely works as its own standalone episode and does well to keep the focus on Team Arrow. 

Excitingly, the episode features a guest appearance from Cynthia Addai-Robinson as shadowy government agent Amanda Waller, and one of the best early Arrowverse villains, Captain Boomerang (Nick E. Tarabay). It's a thrilling installment that demonstrated the appeal of a shared TV universe before the Arrowverse had fully taken shape.

After "Arrow" and "The Flash" became big hits, "Supergirl" was launched in 2015 on CBS. Starring Melissa Benoist as the titular heroine, the series was initially set in its own separate continuity where Kara Zor-El arrives on Earth years after her cousin Superman had been active as a hero in Metropolis. In its Season 2, however, the series moved to The CW and the show was folded into the Arrowverse for the remainder of its six-season run.

In "World's Finest" from Season 1, Kara joins forces with The Flash, who unexpectedly arrives from a parallel Earth. Delighted to be meeting another superhero, Kara introduces Barry to her friends and together they try to find a way to send him home. At the same time, though, the villainess Livewire (Brit Morgan) unites with a young woman named Siobhan (Italia Ricci). After the newcomer discovers that she also possesses strange abilities, she becomes known as the Silver Banshee, and the two evildoers set out to get even with Supergirl. To do it, they kidnap Catco CEO Catherine Grant (Calista Flockhart) to draw both Kara and Flash out into the open. 

Though Kara's meetings with other heroes would become common later on, "World's Finest" is her monumental first meeting with another iconic hero. It also proved to a new, perhaps skeptical audience that "Supergirl" was here to stay with the Arrowverse stamp of approval.

The Arrowverse has done more than just pay homage to stories from classic DC Comics, but it's also tipped its hat to the long history of DC heroes on the screen. Early in the franchise's run, this meant bringing back John Wesley Shipp — the star of 1990's "The Flash" – as Barry Allen's father, Henry. And in the Season 1 episode "Tricksters," Shipp is reunited with one of his old TV nemeses.

The episode sees a new villain emerge calling himself The Trickster (Devon Graye), who takes his name from a master criminal who's been sitting in prison for 20 years. To stop this new threat who has been detonating bombs across the city, The Flash visits with the incarcerated former Trickster, "Silence of the Lambs"-style. But things go terribly wrong when the original Trickster is set loose and allies himself with his successor. Together, the two arch criminals kidnap Barry's father in a fiendish plot to destroy Central City.

Beyond just a simple nod to an old series, "Tricksters" sees the return of guest star Mark Hamill, who played the Trickster on the 1990 run of "The Flash." With its nostalgic casting and a few genuine surprises, it's one of the best episodes of the inaugural season of "The Flash." 

The first true spin-off in the Arrowverse, "Legends of Tomorrow" was a wholly original idea that grew out of various recurring characters in "The Flash" and "Arrow." The series is focused on a rotating team of superheroes (and sometimes villains) recruited by a time-traveling agent from the future named Rip Hunter (Arthur Darvill). Even occult investigator John Constantine (Matt Ryan) joins the crew after his own series on NBC was abruptly canceled. Running for seven seasons, the show's best is "Invasion!," a story inspired by a company-wide crossover event in the comics originally published in the late 1980s.

Like it's comic book source material, "Invasion!" is a crossover story that sees Supergirl, the Flash, and Arrow unite with the Legends of Tomorrow team — then consisting of the Atom (Routh), White Canary (Caity Lotz), Firestorm (Franz Drameh/Victor Garber), Vixen (Maisie Richardson-Sellers), Steel (Nick Zano), and Heat Wave (Dominic Purcell). Working together, they must stop an intergalactic alien race called the Dominators from attacking Earth. 

The final entry in a four-part story, the finale sees Professor Stein (Garber) discover the means to thwart the Dominators, only to also discover an aberration in the timeline that he may ultimately be responsible for. Once again, an epic multi-part saga elevates the action, as "Invasion!" rewards longtime viewers of the Arrowverse with its many connections and crossover characters. 

In the Arrowverse, not every episode that crosses into a parallel reality involves meeting heroes from another TV series. "Escape from Earth-2" is a Season 2 episode and the second half of a two-part story in which Barry Allen travels to Earth-2 on a mission to rescue Jesse (Violett Beane), the daughter of Harrison Wells (Tom Cavanagh). Barry takes on the role of his alternate reality counterpart and discovers that some of those he calls friends on his world are his enemies on this one. 

We also get an appearance from Jay Garrick (Teddy Sears), the Flash of that world, who teams up with Barry to stop the villain known as Zoom, an evil super speedster himself. The episode begins with Barry, having failed his mission, taken prisoner by Zoom alongside Jesse. But to escape and stop the villain's diabolical plans, Barry will need the help of those on Earth-2, including his own double who has lost his speed powers. Stuck in Zoom's prison alongside Barry and Jesse, there's a mysterious man in an iron mask who can offer only a strange and cryptic message. Who is he, and could he hold the key to defeating Zoom?

Tying together multiple storylines across two worlds, "Escape from Earth-2" is part of the larger multiverse tapestry that makes the Arrowverse such a groundbreaking serialized tale. Take a deep breath before watching, though, because your jaw will be on the floor by the closing credits.

Once again, the next entry on our list of best episodes in the Arrowverse is an entry in a massive multi-part event. At this point in the franchise, the multi-show meetings were practically annual events, just like in the comics. In 2017, the series-spanning story was "Crisis on Earth-X," and it began in this episode of "Supergirl." 

The epic adventure opens on a twisted alternate Earth where the world is ruled by Nazis. Their leader is none other than the archer known as Dark Arrow — a sinister version of Oliver Queen — who leads the New Reichsmen against the rebel heroes known as the Freedom Fighters. The good guys have created an interdimensional portal and are hoping to banish Dark Arrow and his New Reichsmen to a parallel dimension, but when they do, it means trouble for the heroes of Earth-1. Now, The Flash, Arrow, and Supergirl — visiting from Earth-38 — must face off with Nazis from another world who've teamed up with the evil Eobard Thawne.

Inspired by a similar comic book storyline published in the 1970s and possibly influenced by more recent DC stories based in the same bleak alternate Earth, "Crisis on Earth-X" introduces a host of new heroes into the Arrowverse. It also again demonstrates that mind-blowing multiversal madness was the key to greatness by topping previous event stories in scope and scale.

With an impressive number of heroes from the DC Comics making their way to the Arrowverse during its decade on the air, it might be hard to pick the best one. But when it comes to villains, there are a few that stand out above the rest, and the finest might be Manu Bennett as Slade Wilson, the merciless assassin known as Deathstroke. He's first introduced early in the series as a quasi-mentor to Oliver Queen, and we learn through extensive flashbacks that Wilson was marooned on an island with Oliver and trained him in the skills he'd eventually use as the Green Arrow.

Later, Oliver saves Slade's life by giving him a serum that enhances his abilities, and it's in "Deathstroke" — Season 2's 18th entry — that we see the culmination of his transformation into his costumed comic book counterpart. Having been a thorn in the side of Team Arrow for some time, he's now ready to put a final plan in motion that could wipe out Oliver and his friends for good. 

Stringing together multiple ongoing plotlines that have been running through the series for a while, the episode also sees Moira (Susanna Thompson) continuing her run for mayor, and a major revelation for Thea (Willa Holland) regarding the truth about her father. But the real highlight of the episode is Bennett as the master criminal who arms up and adopts his Deathstroke identity for the first time.

In 2016, the annual Arrowverse mega-crossovers began with "Invasion!" and continued a year later with "Elseworlds," a story that introduces Batwoman and allows different characters to swap roles. In 2018, a year before "Crisis on Infinite Earths" reshaped the multiverse, the annual event was "Crisis on Earth-X," which comes to a conclusion in an episode of the spin-off series "Legends of Tomorrow."

In the previous installments, it has been revealed that the Nazi version of Supergirl is dying, and Kara gets kidnapped to provide organs to save the life of her evil doppelganger. Meanwhile, Oliver goes undercover as the evil Dark Arrow, and after leading the villains of Earth-X back to Earth 1, unites with the other heroes to save their Supergirl. But the death of one of their own prompts the heroes of Earth-1 to wage an all-out war on Earth-X, and in a climactic battle, a virtual army of superheroes faces off against an army of Nazis. In a special treat for fans, we also get to see the likes of Arrow and Supergirl clash with their evil Nazi counterparts. 

The biggest episode in the Arrowverse yet, "Crisis on Earth X, Part 4" ends with a hero from Earth-X joining the Legends of Tomorrow.

Sure, the multiverse event episodes remain some of the most celebrated entries in the Arrowverse, but a story doesn't have to be a crossover extravaganza to be great. And the "Arrow" episode "What We Leave Behind" demonstrates that a character-focused episode punctuated by plenty of action can be just as good or better than a crossover. This one's a Season 5 mid-season finale, and forces Team Arrow into an impossible situation against a deadly foe whose origins are tied to a story from all the way back in Season 1.

First, complicated vigilante Artemis (Madison McLaughlin) teams with longtime enemy Prometheus (Michael Dorn), providing valuable intel on Oliver Queen and his associates. Just as the gang is preparing for some holiday fun and stumbling over some awkward romantic entanglements at the same time, the villains put their plan into motion. Before the heroes realize what's happened, they learn that their secret identities have been compromised.

But that's not all: "What We Leave Behind" also reveals that Arrow's own past may have inadvertently created one of his worst enemies, and Oliver must grapple with the fallout. It's another example of how the show expertly weaved in regular flashbacks to Oliver's past that tie into current events, a narrative device that helped set the series apart (even if they borrowed it from "Lost"). 

Out of all of the Arrowverse shows, "Legends of Tomorrow" is the one that leans the hardest into science fiction. In "Here We Go Again" — an episode from the show's Season 3 — we get a staple of the sci-fi genre: a time-loop episode.

The problem occurs while Zari (Tala Ashe) is working on repairs to their time-jumping ship, the Waverider. She has plans for a new program to detect problems in the timestream, but just as the rest of the team returns to the ship, the program malfunctions, and the group gets stuck in a repeating loop of time. In this circular sequence, Zari's continued attempts at making repairs results in the ship's destruction, and if they can't find a way to escape the loop, they'll be stuck repeating their own deaths forever.

One of the most common tropes in sci-fi TV, time-loop episodes rarely disappoint. "Here I Go Again," while hardly the only time-loop story in the Arrowverse, is definitely the best. It's also one of the better overall episodes of "Legends of Tomorrow" and the entire Arrowverse.

Following up on events from previous episodes, Dr. Harrison Wells from Earth-2 has been successful in stealing some of the Flash's powers. But Wells isn't the real villain this time, because he's been blackmailed by the villainous time-jumping speedster Zoom who has taken Wells' daughter Jesse captive in his home reality. Now in "Welcome to Earth-2," Barry has agreed to help Harrison go back to the parallel Earth and help him save his daughter. But in his first visit to this alternate world, Barry must deal with shocking twists of fate that throw him for a loop.

Arriving on Earth-2 with Wells, Barry becomes trapped there when the last breach at S.T.A.R. Labs is destabilized. Thankfully, Zoom is stuck on the other side, giving them time to save Jesse. In the meantime, Barry learns more about this alternate reality, and is gobsmacked to discover that Iris West isn't just a skilled detective, but also his counterpart's wife. But the real shocker is when he finds out that his friends Caitlin Snow (Danielle Panabaker) and Ronnie Raymond (Robbie Amell) are not his friends on this world, but enemies known as Killer Frost and Deathstorm, and they're working for Zoom.

A weird and wild alternate world episode that shakes up the show's status quo, "Welcome to Earth-2" sets up an even better finale that shows up later on this list. But more than that, the story also forces Barry to re-evaluate his own friendships by coming face to face with what could be.

Don't be fooled by the presence of Barry Allen — the "Arrow" episode "Three Ghosts" isn't a crossover episode with "The Flash." That's because Barry's early appearances in the Arrowverse actually came well before he received superpowers and became the Scarlet Speedster. In Season 2 of "Arrow," Allen is first introduced in the episode "The Scientist" as a police forensics expert who comes to Starling City on a case and impresses Oliver Queen and Team Arrow with his investigative skills. 

In this episode, "Three Ghosts," Barry finds himself unexpectedly knocked out and awakens in Arrow's lair. There he is met by Arrow's ally Felicity Smoak (Emily Bett Rickards), who needs Barry's help to save Oliver's life as he lies dying from injuries sustained in a brutal fight in the previous episode with the villain called the Acolyte (Graham Shiels). Though Allen saves Oliver, Arrow isn't happy to have his identity exposed ... but that's the least of his worries. Thanks to the unorthodox emergency treatment that Allen administers, Oliver begins suffering vivid hallucinations that take the form of figures from his past. 

Forced to confront his own mistakes, Oliver must deal with deep emotional scars if he is to survive. An Arrowverse take on "A Christmas Carol," this Season 2 episode is a powerful emotional journey and helps establish the bond between Oliver and Barry.

Great TV shows often save the best for last, and the Arrowverse is no different, as the Season 2 finale "Unthinkable" nabs a spot on the franchise's best episodes. "Unthinkable" sees recurring friend-turned-foe Slade Wilson — who will one day become the masked mercenary Deathstroke — enact his plan to destroy everything that Oliver Queen holds dear. The story picks up with sidekick Roy Harper having almost entirely lost his sanity due to the effects of a serum that granted him extra-human abilities.

With a cure administered, though, Roy awakens, seemingly back to his old self and able to aid Arrow in defending against an attack from Slade and his foot soldiers. But when Oliver's on-again-off-again lover Laurel (Katie Cassidy) is taken prisoner, Arrow goes over the edge in his battle against Slade and risks crossing the line between good and evil.

In a stunning final showing for the series' second year, flashbacks continue to shed light on Oliver's origins, including his first meeting with the enigmatic government agent Amanda Waller.  At the same time, while Roy is finally healed, he faces new problems including a bout of amnesia, and struggles to understand what has happened to him.

In the early days of "The Flash," one of the biggest stories was that of Eobard Thawne — the Reverse-Flash — a major villain from the comics. He's also revealed as the mystery man responsible for the death of Barry's mother, an incident that defines Barry's very existence as he uses his powers to hunt for her killer. 

In the midseason finale of Season 1, "The Man in the Yellow Suit," audiences get their first major glimpse at the villain. It comes in an electrifying confrontation where we learn that the evil speed demon has somehow been a thorn in Flash's side all his life, yet Barry doesn't understand how that could be. At the same time, we learn the secret of a new meta-human on the scene, which turns out to be Ronnie Raymond, who has discovered he has fiery powers of his own. 

That's not the only major revelation regarding a friend in Barry's orbit, though, as this installment is capped off with the mind-blowing twist that the Reverse-Flash is, in fact, one of Barry's closest allies — a secret revealed only to the audience. A story with long-lasting ramifications, "The Man in the Yellow Suit" turns the series on its head en route to becoming a fan favorite.

Prior to the Arrowverse, superheroes on TV didn't usually rock the boat with unpredictable stories from season to season. With a few notable exceptions, superhero TV preferred a more traditional adventure-of-the-week format. But "Arrow" bucked tradition and went the serialized route, and nowhere is the show's willingness to upset the apple cart more visible than in its Season 7, in which the Green Arrow publicly reveals his secret identity and serves time in Slabside Penitentiary for his crimes as a masked vigilante. "The Slabside Redemption" is the best episode of this milestone storyline.

Episode 7 of Season 7 is also the finale to the prison story, as Oliver has had to deal with violence and turmoil behind bars. Now, just as he is preparing to be released from his sentence, his family and friends on the outside come under threat from drug lord and fellow prisoner Diaz (Kirk Acevedo). When warnings to the authorities go unanswered, Oliver realizes his only option may be to break out of the slammer and save them himself. 

In Diaz's final attempt to stop him, though, he sparks a prison riot, and suddenly Oliver must fight to the death to save his friends without risking his impending freedom. A different kind of story that takes Oliver far out of his element, "The Slabside Redemption" turns "Arrow" into a tense prison drama.

Early Season 1 episodes of "The Flash" are some of its best, and that includes one called "Flash vs. Arrow." It's exactly what you'd expect from its title — a crossover with sister-series "Arrow," the first in what eventually becomes an annual event. It also gives us an unexpected and epic clash between the two stalwart heroes, as Flash comes under the control of a meta-human villain.

The action starts as Central City is under siege from Roy G. Bivolo (Paul Anthony), a criminal with the power to control his victims' minds and send them into an uncontrollable rage. While Flash and his friends struggle to stop him, Oliver Queen arrives in hot pursuit of a mysterious baddie of his own who uses boomerangs as his weapon of choice. Agreeing to team up to catch both targets, Flash and Arrow work together, but not before Bivolo uses his power to turn them against each other. Ultimately, they get the job done, but Oliver believes Barry still has some growing up to do if he wants to become an accomplished crime fighter.

With an early mention of the Suicide Squad, too, "Flash vs. Arrow" succeeds beyond all expectations, establishing a unique rapport between the two heroes that borders on mentor and protege. As the two inaugural Arrowverse series come together, it also sets a powerful precedent for every crossover that would follow.

It's not always the big revelatory episodes that prove to be the best — sometimes, it's the follow-ups that deal with their aftermath. Such is the case with "The Trap," from Season 1 of "The Flash," which deals with the ramifications of Team Flash's discoveries about the future. They've learned about the events in 2024 via a future newspaper article held within a secret vault located within S.T.A.R. Labs.

But not everyone is convinced that all of this is true, as many — including Eddie Thawne — continue to doubt the reality of time travel. Though the episode has some out-there moments — including Cisco's (Carlos Valdes) dreams turning out to be memories of an alternate reality — the episode is a clever, plot-twisting adventure that's as fun as any in the series. With plenty of answers to long-standing questions and some of the season's tensest moments, "The Trap" is one of the best entries in "The Flash" Season 1.

No, we're not talking about logging in to your next video conference call, we're talking about the Episode 6 in Season 2 of "The Flash," titled "Enter Zoom." Introduced in that season's premiere installment, Zoom is the big bad and overarching villain of the year — a dark version of The Flash himself. Voiced by Tony Todd — the actor who played the monstrous killer in "Candyman" — he's an intimidating and downright terrifying megalomaniacal speedster out to destroy all others, and it's in "Enter Zoom" where Barry and Team Flash come face to face with him for the first time. 

The climax of a multi-episode arc that first introduces the concept of parallel Earths, "Enter Zoom" is a thrill-a-minute adventure that sees Barry teaming up with Jay Garrick — the Flash of Earth-2. He's been pulled into Earth-1 while in the middle of a battle with Zoom, and now he needs Barry's help to take the villain down. But to do it, the two Flashes have to first defeat the villainous Dr. Light (Melise), because she is key to an elaborate plan to capture Zoom and drain him of his powers. It's easier said than done, however, and when Light escapes, Barry and his team must improvise. If they're not careful, they all could end up dead in the blink of an eye. 

A season finale can often be the best story of the show's year, pulling together ongoing plots to make for an explosive, fan-pleasing climax. But the capper to Season 1 of "Arrow" goes for something different. A more intimate story than you might expect from the season finale of an action show, "Sacrifice" puts Oliver Queen in the crosshairs of the year's big bad, Malcolm Merlyn (John Barrowman). It also completely upends audience expectations and throws more than one curveball.

Held captive by Merlyn, Oliver is chained up and helpless while he's interrogated by a ruthless foe who always seems to have his number. Despite being on his own at the hands of Merlyn, though, Oliver is anything but alone, as the rest of Team Arrow works tirelessly to save him. But while a battle of wills between hero and villain plays out in Merlyn's lair, we get the meat of the action through flashbacks where Oliver and Shado (Celina Jade) are caught in a pitched final battle with the mercenary Fyers (Sebastian Dunn).

A dramatic finale, "Sacrifice" lays the groundwork for everything that will follow. And it's all capped off with a tragic death, a show-stopping revelation, and a confrontation that has been brewing all season long.

The Arrowverse was built on a foundation of ongoing storylines, often played out across multiple seasons, and in "Fast Enough" — the first season finale of "The Flash" — the first major arc closes out. The debut season had been largely focused on Barry Allen's attempts to find his mother's killer, with Barry eventually learning that the murderer is a speedster from the future called the Reverse-Flash. But he's recently discovered that the villain is actually Dr. Harrison Wells, whose real name is Eobard Thawne. 

Now, in "Fast Enough," Barry has Thawne imprisoned, and the villain makes a deal with him — if Barry brings him back to his own time in the future, he'll give Barry the chance to save his mother's life. But the mission to change history comes with enormous risks — If Barry doesn't stop the murder before it occurs, the breach to the past could become a black hole that swallows up the entire city, or worse. 

The real surprise comes, however, after Barry arrives in the past with the chance to finally save his mother's life. There, his future self warns him not to go through it, because the effects of changing the timestream could be more catastrophic than anyone could ever imagine. Faced with that dire warning, a villain who killed his mother, and a chance to undo it all, it may take an act of ultimate sacrifice to stop Thawne and save the city.

Another mid-season finale, "The Climb" is an unconventional episode of "Arrow" that utilizes both flashbacks and flash forwards as Oliver deals with the death of Sarah Lance, a member of the League of Assassins. Her killer remains unknown, and now their leader — Ra's al Ghul (Matt Nable) — demands that Oliver hunt down the person responsible. Given 48 hours to find Sarah's murderer, Ra's threatens to kill 50 innocent people in Starling City if Oliver fails.

As Oliver and Team Arrow race to find the truth, evidence begins to point to an unlikely suspect. Soon, though, Thea Queen enters the picture as another possible candidate to be the killer, and Team Arrow becomes increasingly frustrated that Oliver won't accept the evidence of her guilt. While some try to keep Sara's death a secret, new truths are revealed, including Thea's odd involvement with Malcolm Merlyn.

The first full appearance of Ra's al Ghul, a villain who has lurked in the background of the series for years, "The Climb" sees Arrow face down the leader of the League of Assassins for the first time. It's an emotional tour de force, revealing the heartbreaking identity of the mysterious Scarab, and a fight between Arrow and his sister. But the most powerful sequence is Oliver's arduous test of endurance.

Close enough to the top spot that it easily could have been ranked as the best episode in the Arrowverse, "Out of Time" is indisputably top dog when it comes to "The Flash." In this first segment of a two-part story, we meet Mark and Clyde Mardon (Liam McIntyre and Chad Rook), a pair of criminal brothers who are separated when their plane goes down as the result of a disaster at S.T.A.R. Labs.

Two years later, Mark Mardon resurfaces, gifted with the power to control the weather, creating everything from spontaneous ice storms, lightning, and more. Believing his brother dead in the crash years earlier, he's returned to exact vengeance upon those he believes are responsible, which includes Barry's father figure Joe West (Jesse L. Martin). Joe goes after the madman, but Flash knows he's the only one who can stop him. While the Weather Wizard is wreaking havoc on Central City, Cisco has also found evidence that points to the identity of the Reverse-Flash.

Of course, what really puts the cherry on top is when "Out of Time" does the unthinkable and opens the Arrowverse up to the concept of time travel. Using his powers to go faster than ever before, Barry ends this episode finding himself in the past, creating a potential alternate timeline.

The finest episode in the history of the Arrowverse, the champion of nearly 700 installments, "Lian Yu" is the season finale of Season 5 of "Arrow." It concludes what is perhaps the best season of the series — maybe even the best single season in the Arrowverse entirely — as the villainous Adrian Chase (Josh Segarra) finally takes his vendetta against Green Arrow to its end. And their final fight takes place on Lian Yu — the same island nation where Oliver had been stranded for years, and where he'd taken his first steps towards becoming a hero. 

The episode opens with Oliver's friends trapped on the same island he once called home. To save them, he'll have to go toe to toe with the vengeful Adrian Chase, but he'll have the help of mentor-turned-villain Slade Wilson and Digger Harkness, aka Captain Boomerang, in an unlikely alliance. But if he's going to win the day, Oliver will have to do more than defeat his foe, but he also must find a way to come to terms with his own past.

An Earth-shattering installment in more ways than one, "Lian Yu" doesn't just wrap up Season 5, but turns over a new leaf for the entire series. It says goodbye to the flashbacks of Oliver's time on the island, leaving audiences with an entirely new path for the series to tread. A mouth-watering cliffhanger, it also leaves the fate of much of the main cast up in the air.