The NCIS: New Orleans Episodes With Original NCIS Cast Members

The "NCIS" universe is a long-running and expansive one, thanks to its 18 years or so on the air and several spinoff procedural dramas, including the upcoming "NCIS: Hawaii." The first offshoot, "NCIS: Los Angeles" is still on the air, of course — and as fans know, the show's universe also includes past and present shows like "JAG," "Hawaii Five-O," "MacGyver," "Magnum P.I.," and "Scorpion." However, the shared universe is about to change shape slightly as a result of the cancellation of "NCIS: New Orleans," which will air its last episode in May after a seven-year run headed by executive producer and star Scott Bakula.

One big advantage of the shared universe concept is that it allows actors and their characters to appear on other shows within the same world. And that can help new spin-off shows gain a grounding, or allow characters from canceled shows to move around, or do other creative things designed to bolster the ratings and please the fans of all the series involved. That has definitely taken place in the past, as characters from the regular "NCIS" cast have crossed over to "NCIS: New Orleans" for a change of pace.

For example, Mark Harmon, as Leroy Jethro Gibbs, has appeared in numerous episodes of the spinoff series, often uncredited. Diane Neal, who plays the recurring character Special Agent Abigail Borin, appeared on both shows in a total of nine appearances between 2010 and 2015. Leon Vance, played by Rocky Carroll, has also crossed over a few times in his role as a director of NCIS. Leslie Hope, who plays U.S. Secretary of the Navy Sarah Porter, has also appeared in both series. But it's super-special when regular cast members move over for an episode or two. Here are the "NCIS: New Orleans" episodes that have hosted the regular stars from the main series.

When "NCIS: New Orleans" started its run in 2014 with "Musician Heal Thyself," it was imperative that continuity be provided by incorporating a character or two from the original series. Enter fan favorite David McCallum, known to "NCIS" fans as Dr. Donald "Ducky" Mallard. As Dr. Loretta Wade (CCH Pounder) is trying to put the pieces together regarding the death of a petty officer named Calvin Parks that Dwayne Pride (Bakula) once mentored, she has questions about an unusual tattoo that seems to link him to gang activity. 

Wade remembers a similar case out of Washington and sees that Mallard was the coroner involved. She looks forward to the chance to catch up with an old colleague, and the two of them together, consulting remotely, realize that the tattoo was placed posthumously in order to throw investigators off the track. Mallard's role is a small but important one, breaking the case wide open.

An entire cadre of "NCIS" actors appeared in the second episode of "NCIS: New Orleans," "Carrier," which was inspired by an episode from the original series that helped ground the spinoff as part of the shared universe early in its run. In the episode, the team investigates the death of a Navy lieutenant after he's hit by a taxi while out in downtown New Orleans. They can't find a motive, but soon discover that the victim had bubonic plague — and it's no accident. 

To prevent the situation from escalating further, director Leon Vance calls in reinforcements, and the team is assisted by the Navy and NCIS stalwarts Abby (Pauley Perrette) and Tony (Michael Weatherly) — who was previously exposed to a particularly virulent strain of the plague, making him (as he notes in the episode) the "Plague Whisperer." They team up to try to find all the sailors who are on leave in the city who may be affected, while also trying to figure out who's responsible for the bio-terrorist attack that caused the sickness. Carol Wilson (Meredith Eaton), a recurring character on three episodes of "NCIS" representing the CDC since 2009, also appeared in the episode.

If you recall Abby Sciuto's backstory, you'll know she was born in New Orleans and adopted by a family there, so in 2016, there was an opportunity to bring Abby home for a second season episode, "Sister City: Part 2" that featured Pauley Perrette as Abby, Mark Harmon as Gibbs, Brian Dietzen as Jimmy Palmer, Emily Wickersham as Ellie Bishop, and David McCallum as Mallard.

In the episode, the team deals with the aftermath of a Russian counselor's murder by poisoning. Ellie accompanies the remains to New Orleans for an autopsy, while Abby and the others investigate a Russian sleeper agent that appears to be involved with Abby's adopted brother, Luca. She gets involved to make sure he's alive and to prove he's no criminal. Sadly, Perrette has since left the "NCIS" universe, but her presence remains a strong one on the show — and luckily, fans have plenty of reruns to watch if they're missing her too much.

In 2017, a few members of the main "NCIS" crew crossed over in a television event that started in "Pandora's Box Part 1," a regular episode that served as the first part of a two-part February sweeps stunt. In this second part of the story, Timothy McGee (Sean Murray) and Nick Torres (Wilmer Valderrama) come to help the New Orleans group look for a terror playbook from Homeland Security that's been stolen. In fact, Torres gets arrested while working undercover and getting in the way of a murder investigation, and that serves as his introduction to the team. McGee has a slightly more dignified entrance, striding into the New Orleans office after celebrating Mardi Gras, as evidenced by the fact that he's wearing a bevy of beads. 

Mark Harmon as Gibbs briefly appears in the episode as well via phone and large screen, talking to Bakula's Dwayne Pride and offering to run interference with the suits. "You always had a gentler way with the suits," Pride tells Gibbs, leading McGee to laugh — only to realize it's not a joke. Yikes.