The 5 Strongest Marvel Villains Who Haven't Yet Appeared In The MCU

For every incredible hero in the Marvel Universe, there seems to be a worthy villain capable of taking them on, if not destroying them. From street-level bad guys like Bullseye or the Jackal to cosmic entities such as the Beyonder, Marvel foes operate with varying degrees of power. But more than a decade and a half since "Iron Man" kicked off the Marvel Cinematic Universe, many of Marvel's strongest and most notable villains still haven't debuted on-screen.

Audiences have met some astonishingly mighty villains, of course. From Thanos (Josh Brolin) gathering the Infinity Stones and snapping half of life out of existence in the "Infinity Saga," to different variants of Kang the Conqueror (Jonathan Majors) appearing in multiple projects, to Ego the Living Planet (Kurt Russell) nearly terraforming entire worlds with his Celestial powers in "Guardians of the Galaxy Vol. 2," the MCU hasn't lacked for powerful villains. But there are still plenty of iconic faces who have yet to make their debut.

Looking at the future of the MCU, five Marvel Comics villains who haven't appeared stand out as solid options to cause considerable problems for the heroes across the multiverse — and any one of them could change the hierarchy of who is considered the most powerful bad guy on the big and small screen.

The Fantastic Four are coming to the Marvel Cinematic Universe, and with their arrival, one of Marvel's most powerful villains, Galactus, should eventually appear as well.

Debuting in "Fantastic Four" #48 (by Jack Kirby, Stan Lee, Art Simek, Joe Sinnott, and Sam Rosen), Galactus is a planet-consuming cosmic juggernaut who serves a vital role of balance in the universe. Originally a mortal man named Galan from the planet Taa, he is transformed into the larger-than-life Galactus during the birth of the Seventh Cosmos. Armed with the Power Cosmic, Galactus is an omnipotent being with unlimited cosmic energy that allows him to feast on planets and destroy them with ease. The Devourer of Worlds is seen as a nefarious force by many, but his consumption of celestial bodies to feed his hunger is an important part of the universe's cycle of rebirth, creating vacuums where new worlds can rise.

Galactus' heralds — beings he imbues with the Power Cosmic to do his bidding — locate worlds to satisfy his hunger. Still, destroying entire planets has placed him at odds with heroes and villains, as his hunger outweighs any emotional pleas or reasoning from those being annihilated.

It would make a lot of sense for Galactus' first appearance to occur in the upcoming Fantastic Four film directed by Matt Shakman. Adapting the story of his arrival on Earth accompanied by his most famous herald, the Silver Surfer, would properly introduce the villain while setting him up as one a primary antagonist of Phase 6 of the MCU. The looming threat of Galactus could be similar to Thanos' first tease in "The Avengers," with the threat of his eventual return setting several epic events in motion.

Of course, the Fantastic Four's imminent Marvel Cinematic Universe arrival means another incredibly powerful villain will show up: Doctor Doom.

First appearing in "Fantastic Four" #5 (by Jack Kirby, Stan Lee, Joe Sinnott, Stan Goldberg, and Artie Simek), Victor Von Doom is a former friend turned rival to Reed Richards. Doom's attempts to outwit Richards through technological and scientific innovation end up causing an explosion that leaves his face permanently scarred. As a result, Doom develops a lifelong vendetta against Richards, blaming the FF's leader for turning him into a monster.

Doom's return to his home country of Latveria morphs him into full-blown villainy as he seeks revenge on Richards, using the country's resources as its ruler to develop his own army. At the same time, Victor continues his mastery of the dark arts, becoming one of the most skilled sorcerers on Earth. With his genius intellect, expertise in magic, and a legion of Doombots by his side, Doom's powers, both personal and political, are vast and intimidating to any hero.

With "Avengers: Secret Wars" apparently set to adapt Marvel's "Secret Wars" (by Jonathan Hickman, Esad Ribic, Ive Svorcina, and Chris Eliopoulos) comic, the Latverian monarch's role in crafting Battleworld in the face of the near-collapse of the entire multiverse seems destined to get the big screen treatment. It's not controversial to say 20th Century Fox's previous "Fantastic Four" adaptations didn't do the character justice. Now, the MCU could show how terrifying the villain truly is — it's about time audiences saw Doctor Doom at his best.

With the power of a million exploding suns and more god-like abilities than practically any Marvel hero, the Sentry's powers are largely unrivaled. Unfortunately for the world and universe, the incredible powers of the Avengers' Golden Guardian come with an evil opposite named the Void, an entity that represents the hero's darkest side.

Debuting in "Sentry' #1 (by Paul Jenkins, Jae Lee, Jose Villarrubia, Richard Starkings, and Wes Abbott), the Void is a being the Sentry (and the rest of the Avengers) have gone to great lengths to repress. The Void possesses many of the same powers as Sentry, but as dark reflections of his most heroic form. That means the entity has similar god-like abilities, but instead of using them for good, it prefers to try to destroy the Marvel Universe — and is fully capable of doing so.

If the Sentry loses control, the Void can take over the hero's body and cause significant damage. While it can be killed, its return is always inevitable. The Void's potential emergence is so dangerous that Sentry has teamed up with his fellow heroes to wipe his mind in an attempt to completely bury his entire super-powered self, as the risk of the Void emerging is simply too much. At full power, even the mightiest Avenger stands little chance against it.

The Sentry is set to appear in the upcoming "Thunderbolts" film, despite Steven Yeun walking away from the project after initially being cast as the complex hero. Regardless of who plays him, viewers will likely see Sentry's dark side emerge, and the Marvel Cinematic Universe will feel the wrath of the Void.

Knull is a relatively new addition to the Marvel Universe, first appearing in 2018 during Donny Cates and Ryan Stegman's run on "Venom." But in a short amount of time, the God of Symbiotes and King in Black has proved he belongs in the upper echelon of powerful villains.

An ancient being with ties to Celestials, Knull was initially appointed by the space gods as the King in Black and the opposite of the Beyonders. However, he had different plans. Knull turned on the Celestials, killing one (inadvertently creating Knowhere) and forging All-Black the Necrosword. These events also served as the beginning of symbiotes (which ultimately led to Venom's creation), which he used as a corrupting force of control over others.

The King in Black is a powerhouse with many god-like powers, headlined by his ability to command symbiotes. Knull is so powerful, he's one of the few beings ever to take on Sentry and brutally kill the hero, singlehandedly. Knull once nearly took over Earth, transforming its greatest heroes into his own army, commanding a fleet of symbiote dragons, and enveloping everything in darkness, with his defeat only coming on the verge of the planet's destruction.

If Marvel and Sony want to turn Venom's story into a cosmic epic battle between good and evil, Knull represents a worthy villain for not just Eddie Brock, but for the greatest heroes across the universe. He would pose a Thanos-level threat that could be a major antagonist for multiple films. Knull's arrival would throw either Marvel's or Sony's universe into utter chaos.

Despite Marvel fans believing Mephisto was being teased throughout "WandaVision," the fan-favorite villain didn't make his live-action debut in the Disney+ series. However, Marvel's satanic bad guy may play a key role in future events, as he's now rumored to appear in "Ironheart," where Sacha Baron Cohen has been linked to the role. If this proves to be accurate, Mephisto's appearance could be a game-changer for the MCU.

Since debuting in "Silver Surfer" #3 (by Stan Lee, John Buscema, Joe Sinnott, and Artie Simek), Mephisto has affected all aspects of the Marvel Universe, from the cosmic to the street-level to the supernatural. The villain's extraordinary powers include magic manipulation, shapeshifting, and the ability to completely change reality. Most famously, he once made a deal with Peter Parker and Mary Jane Watson to trade their marriage to save the life of Aunt May, literally rewriting years of their lives. More recently, he helped Agent Coulson make the Squadron Supreme (Marvel's answer to DC's Justice League) the most important super-team on Earth by erasing the Avengers from existence.

There's no telling how much reality-changing chaos he could cause in the live-action universe. Mephisto is a menace who can't be trusted. In the MCU, he could become an overarching villain, using his demonic powers to manipulate reality and present a world that isn't as it appears. If Mephisto does head to the live-action realm, it would also open the door for several other supernatural characters to join him, introducing audiences to a whole new side of the MCU.

Picking five of the strongest villains among thousands of Marvel's comic book bad guys is a difficult task, as there's no way to not skip a character worthy of consideration. Powers are often subjective and heightened or lowered by who is writing them and what story they appear in. We ultimately went with five bad guys who seem destined to show up in the live-action universe one day.

In determining the strongest foes for this post, the first criterion was that the chosen villains couldn't have debuted in the Marvel Cinematic Universe already. Outside of Galactus, the list didn't deal with cosmic beings or those who operate as a primary force in the universe. The selected villains have all gone toe-to-toe with some of Marvel's biggest superteams, ranging from the Fantastic Four to the Avengers. At the same time, the villains chosen have a wide range of powers, from the supernatural, cosmic, and magical sides of the Marvel Universe.

The list isn't above scrutiny, as choosing five villains was a tremendously challenging task. Arguments and cases can be made for many characters who didn't make the cut. As such, any list like this is never going to be perfect, considering the amount of debate that can be had around the selectees. However, each character chosen could potentially bring with them something new and exciting that the MCU hasn't seen before.