the best NCIS episodes, filled with tension, mystery, and high emotions. From dangerous masterminds to traitorous insiders, their actions test the team’s skills, keeping viewers hooked with every twist.

The iconic series is part of a larger world, with 8 spinoffs in the NCIS franchise, each offering new curveballs and fresh characters. Since 2003, NCIS has built a powerful legacy of captivating, edge-of-your-seat action that continues to draw in fans, with its legendary foes raising the bar.

10 Michael Rivkin

NCIS Season 6

Michael Rivkin, played by Merik Tadros, is arguably one of the most memorable and controversial villains on NCIS. He first appeared in the sixth season of the iconic show as an undercover Mossad operative. Rivkin comes to the U.S. with questionable motives after Eli David (Michael Nouri), the head of Mossad, instructs him to do so, eventually putting him on NCIS’ team’s map.

At first glance, Rivkin is a skilled agent with a romantic tie to Ziva David (Cote de Pablo), one of the core of the naval team. However, it quickly becomes clear that he operates in a morally gray area. While he’s technically on the side of justice, his methods and allegiances conflict directly with strict NCIS protocols. Ultimately, Rivkin’s actions lead to chaos, death, and mistrust between key characters, earning him a rightful place among the series’ worst.

9 Mamoun Sharif

Season 4

Featured in NCIS season 4, Mamoun Sharif is definitely the season’s most dangerous villain, although he was not the only bad guy. Played by Enzo Cilenti, Sharif exuded chilling intellect throughout his time on the screen, which, paired with his brutal tactics, secured him the spot as one of NCIS’ most capable antagonists.

To point out just how influential of a villain Mamoun Sharif was to NCIS, the 2007 episode "Sharif Returns" marked the second time a character's name was featured in the title. The first one was "Kill Ari (Part I)" from 2005, which referenced Ari Haswari.

As one would expect from any noteworthy antihero, Sharif first catches the team’s attention after killing a Marine. His main weapon of choice is biological warfare, which he uses with a level of expertise that makes him a serious threat. Interestingly, he is one of the series’ villains who has managed to outsmart the MCRT squad the most. As a psychological and physical menace, Sharif very obviously enjoyed playing games with Leroy Jethro Gibbs (it’s no wonder that Mark Harmon almost quit NCIS during season 4). However, he ultimately gets killed, which puts an end to his tyranny.

8 Paloma Reynosa

Seasons 7 and 8

As a super-rare female villain in the NCIS universe, Paloma Reynosa (Jacqueline Obradors) stands out as one of the best bad guys the team has ever come across. Paloma is the leader of the Reynosa drug cartel, one of the most dangerous criminal organizations in Mexico. Everything we see her do is motivated by revenge, as Gibbs killed her father, seeking retribution for the deaths of his wife and daughter.

Unlike most other villains who target the NCIS team, Paloma’s motives are deeply personal, making her incredibly dangerous. As she embarks on her vendetta, it’s very clear that Paloma wants Gibbs to suffer emotionally and physically. Additionally, despite an army of armed men behind her, she is primarily a master manipulator who isn’t afraid to demonstrate her skills. By turning Gibbs’ past into a weapon, Paloma gave us one of NCIS’ most gripping story arcs.

7 René Benoit

Seasons 4 and 5

Better known as La Grenouille, René Benoit (Armand Assante) is considered to be one of NCIS fans’ favorite villains. He first appeared in the fourth season of the show, but his storyline spanned multiple episodes and ended in the next chapter. Contrary to many of his kind, Benoit operated with suave sophistication and charm. He is a French (hence the nickname) arms dealer and, perhaps more importantly, the father of Jeanne Benoit (Scottie Thompson), whom Tony DiNozzo (Michael Weatherly) starts dating to get closer to him.

Notably, it was NCIS director Jenny Shepard who got the Benoit pot stirring, as she believed the dealer was responsible for the death of her father. When he died in NCIS season 5, many viewers were left with a sour taste, as his murder wasn't solved and Shepard never took on any responsibility.

6 Kyle Boone

NCIS Season 3

As one of the most sadistic villains NCIS has featured, Kyle Boone (Christopher Shyer) is not that easy to forget. Boone is a ruthless serial killer who makes the mistake of killing a Navy petty officer, after which the NCIS team takes on the case.

Even though he’s portrayed as a merciless sadist, Boone’s on-screen time actually brought a level of psychological horror to NCIS. His intelligence, ability to manipulate, and calculated nature make him an unpredictable and dangerous foe for the team. He was arrested for killing countless women, and barely feeling remorse whatsoever about his crimes. Highlighting just how nefarious he was, Boone was even able to turn his lawyer into an accomplice. The killer made his appearance in the third season, and for those interested in seeing his story, the first five seasons of NCIS will be available on Netflix very soon.

5 Sergei Mishnev

NCIS Season 12

Not only is Sergei Mishnev (Alex Veadov) a villain in his own right, but he is also the maternal half-brother of Ari Haswari, the ultimate NCIS antihero. With such predispositions to evil, it’s no surprise that Mishnev caused some of the biggest dramas the show has seen. Notably, the Russian mercenary is considered to be Gibbs’ archnemesis at the time of his appearance, as Gibbs had murdered Haswari earlier in the show.

Despite often playing Russian characters on the screen, Alex Veadov is actually of Ukrainian-Jewish descent.

His villainous arc begins with the masterfully staged diner murder, which was so well crafted that it took the team quite some time to connect the dots. The case proved Mishnev to be one of NCIS’ most menacing criminals, even though he only lived through one season. Later on, he took on a more physiological approach to torturing Gibbs. Ultimately, he paid the price for his actions and was never mentioned again.

4 Jonas Cobb

NCIS Season 8

First featured in season 8, Jonas Cobb, also known as the Port-to-Port killer, is NCIS’ most underrated foe. He was responsible for a gruesome string of murders that spanned multiple cities and naval installations, which is how he got his nickname. A former CIA operative, Cobb brought a set of enviable skills to his killing sprees, including master manipulation.

Years after his debut, his impact remains hard to beat, even with new NCIS seasons rolling out regularly. Despite his notorious legacy, Cobb is often overlooked in fans’ discussions for unknown reasons. Notably, his kills were not just random acts of violence but part of a twisted game of cat-and-mouse with law enforcement that put the NCIS team to the test. In the end, his tragic past as a failed CIA experiment made him a symbol of systemic failure, not just a monster.

3 Trent Kort

NCIS Seasons 4, 5, 6, 8, and 13

Arguably one of the best villains in the NCIS franchise, Trent Kort stands out as one of the worst characters because he was both an ally and a foe to the team. He was first introduced in the fourth season as a part of the squad tasked with taking down La Grenouille and was ultimately the one who killed him.

Throughout most of his run on NCIS, Kort was a neutral character who, at best, irritated DiNozzo. However, as season 13 rolled around, the former CIA operative openly did a 180-degree turn, becoming one of the series’ most complex antagonists to date. By then, he had committed several murders and had even attempted to kill Ziva. Notably, many were shocked to find out that it was actually Kort who killed Shepard’s father, proving himself to be a serious villain on his own merit.

2 Harper Dearing

Seasons 9 and 10

Harper Dearing (Richard Schiff) is at the top of the pyramid when it comes to NCIS bad guys. While some might disagree, Dearing arguably had one of the most emotionally compelling arcs, making him utterly and tragically relatable. After losing his son to an explosion, Dearing is blinded with revenge and becomes a terrorist. His primary targets are Navy ships, as he believes the organization was at fault for his son’s death.

Despite being featured in a handful of episodes throughout the ninth season and only a single episode in the following chapter, Dearing left an undeniable mark on the iconic franchise and established himself as one of its most notorious bad guys.

Schiff masterfully embodied a civilian turned criminal, blending an air of calmness with underlying madness and thus creating a chillingly complex character we can’t forget. Despite being featured in a handful of episodes throughout the ninth season and only a single episode in the following chapter, Dearing left an undeniable mark on the iconic franchise and established himself as one of its most notorious bad guys.

1 Ari Haswari

NCIS Seasons 1, 2, 3, and 9

Without a doubt, Ari Haswari is NCIS’ most important antagonist. Although the former Mossad officer turned terrorist, played by Rudolf Martin, made his debut in the show’s very first season, his legacy remains unparalleled. Haswari made deadly enemies in the second season of NCIS when he fatally shot Caitlin Todd (Sasha Alexander). Most fans have never gotten over the shocking moment, which was one of the most pivotal scenes in the entire series.

Notably, Haswari is Ziva’s paternal half-brother, which complicates his character’s arc and amps up the drama. Nearly two decades after his first appearance, his legacy is still felt throughout NCIS. He is mentioned in all but one season through season 17, a feat no other villain has conquered. Notably, Ziva kills Haswari in the third season, marking a full-circle moment as she was the one to take Kate’s place in the team after her death.