NCIS has lived through most of its 17 seasons as a structured police procedural where the team sets out to solve a crime, find a villain, and most of the time stop a terrorist on American soil.
However, the best episodes don’t just deal with the one-shot villain of the week format.
NCIS is at its best when the team finds a bad guy so dastardly and villainous that it shakes them to the core.
Unlike many weekly procedural shows, NCIS has never been afraid to kill off a main cast member.
When that happens, the NCIS villain is often vilified by all fans who follow their favorite characters week by week and have often developed a strong connection with these heroes.
With 17 seasons of NCIS out there, the show has introduced some vile villains, and here are the 10 worst villains in NCIS history.
Sahar
The most recent NCIS villain introduced on the show is Sahar, and she did the one almost unforgivable thing.
It was Sahar that caused Ziva (Cote de Pablo) to leave the team and fake her own death.
Sahar was part of a splinter cell that included Ziva’s brother Ari (Rudolf Martin), and when Ziva killed her brother, the cell fell apart. Sahar caused even more problems when she tricked the team into killing a decoy (Mouzam Makkar), who they thought was the real Sahar.
In fact, Sahar was close to Gibbs. It was Sarah (Louise Barnes), Gibbs’s neighbor who had a son named Phineas. This made the entire long-running revenge plan hurt Gibbs more than most.
PTP Killer
The PTP (port-to-port) Killer was the main NCIS villain in Season 8.
He was Jonas Cobb. a former U.S. sailor who was also part of a CIA operation known as Frankenstein, which also included Director Vance. This was a behavior modification program that would allow the person to remain calm in all situations.
Cobb was a success and completed his first mission for the CIA as an assassin, but he broke and ended up disappearing before he showed up later and became a serial killer.
Cobb achieved his place in NCIS notoriety when he murdered Mike Franks in front of Gibbs’s house.
Benham Parsa
The Brotherhood of Doubt was a terrorist group whose primary targets were Gibbs and his team.
The group was the focus of NCIS Season 11 when Gibbs and Tobias Fornell learned that the team was a target, and eventually, they learned that the leader was a man named Benham Parsa.
The Brotherhood bombed a gala that killed several people and left Timothy McGee’s future wife paralyzed from the waist down. The reign of terror finally ended when Parsa allowed himself to be captured with the intent of killing Bishop while in custody.
Mamoun Sharif
Mamoun Sharif first appeared in the Season 4 episode Sandblast, which started with a Lieutenant Colonel murdered in an explosion on the golf course.
However, what frustrates Gibbs the most is that the terrorist Sharif was a CIA informant, and by the end of the episode, he had escaped.
By the time he returned later in the season, he had bigger plans with poison gas called BZ Gas and commit chemical warfare on the entire city.
He planned to spread the poison through $1 bills, and even Gibbs who ends up poisoned, is constantly hallucinating, and almost dies before he has to be saved by Hollis Mann.
La Grenouille
La Grenouille (The Frog) is the main villain through several seasons of NCIS and was deceased NCIS Director Jenny Shepard’s main nemesis.
He is a French weapons dealer who Jenny believes killed her father, Colonel Jasper Shepard.
He was a lot more dangerous due to what his own death caused in fallout for the team. He died one night after meeting with Shepard and Gibbs and asking for their protection. His daughter also accused DiNozzo of killing him, which almost shattered the team.
Most theories point to Jenny killing La Grenouille, which is even more distressing when it turned out he never killed her dad. He was one of NCIS’s most dangerous villains, but also its most complicated.
Paloma Reynosa and Alejandro Rivera
Paloma Reynosa and Alejandro Rivera had a big reason to want Gibbs dead. That made this duo’s placement on this list due to how personal the relationship was between them and the NCIS.
Her father was a drug dealer, Pedro Hernandez, who killed Gibbs’ wife and daughter. This led Gibbs on a mission of vengeance, and he assassinated Pedro and earned his two children’s wrath.
Paloma Reynosa and Alejandro Rivera was Pedro’s son and daughter.
Paloma tried for revenge when she tried to kill Gibbs’ father. Paloma and her brother Alejandro were led to a house, and Alejandro opened fire on it, not knowing his sister was in there, accidentally killing her.
Alejandro went to prison and even tried to kill Gibbs again using his reach, but failed four different times to get revenge for his father’s death.
Trent Kort
Trent Kort was a British national and CIA operative who betrayed the United States and became a thorn in the side of the NCIS team.
His villainy goes back many years, as it was him and not La Grenouille who killed Jasper Shepard, the father of Jenny Shepard. The fact that Jenny might have killed La Grenouille for a crime he never committed shows how evil Kort is.
He also tried to kill DiNozzo with a car bomb and ended up killing La Grenouille instead.
He returned and killed Thomas Morrow, the former NCIS Director before Jenny, and tried to kill Fornell. He is also the man who bombed the David farm, trying to get Mossad Director Eli David and presumably killing Ziva (who survived).
Sergei Mishnev
Sergei Mischnev was an Israeli mercenary that showed up in Season 12 of NCIS.
He had a strong connection with another NCIS villain, as he shared the same mother as Ari Haswari, making them half brothers.
Sergei allied with numerous terrorist groups and then learned about Ari’s murder at the hands of NCIS. As a result, he began to spy on the NCIS team and slowly planned revenge.
He shot down a helicopter that Gibbs and McGee were on, although both survived. He then murdered five people and set up their bodies to mimic the murder of Jenny Shepard.
He killed another man and staged the murder to look exactly like the murder of Michael Franks. He shot Gibbs and Fornell’s ex-wife Diane in the head, a copycat killing similar to that of Kate.
Fornell finally kills him, gaining revenge for the death of Diane.
Ari Haswari
The first time that NCIS fans realized that anything could happen on the show was in Season 2.
In the season finale, Ari Haswari shot Caitlin Todd in the head, killing the NCIS Agent in front of Gibbs and DiNozzo.
Ari was the main villain in Season 2, and then it continued into Season 3, where a Massad Agent named Ziva David showed up. Ziva was Ari’s sister and was there to help NCIS in the manhunt for her brother.
His end finally came when he had Gibbs dead to rights, and Ziva ended up killing her own brother. The moment he killed Caitlyn changed NCIS forever, and he influenced other villains in the future, most specifically Sergei and Sahar.
Harper Dearing
While Ari was the most memorable NCIS villain of all-time, he was not the deadliest or the worst of them all. That would be Harper Dearing.
Harper was the CEO of an investment company that specialized in technology. However, he was also a terrorist who wanted to make the NCIS and Navy pay after his son died in an explosion.
He first appeared in the Season 9 episode Playing with Fire and terrorized NCIS until the Season 10 episode Extreme Prejudice when Gibbs finally killed him.
He killed several people. He forced Gibbs’ close friend Dr. Samantha Ryan (NCIS guest star Jamie Lee Curtis) to go into hiding when he bribed a judge to release her dangerous husband from prison early. He blew up a cargo ship DiNozzo was on.
His actions even resulted in Ducky Mallard having a heart attack.
No one enacted more carnage on the NCIS team that Harper Dearing, the worst NCIS villain of them all.
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