The NCIS team has faced some pretty tough foes over the years. There have been killers galore, but the worst villains are the ones who come directly after the NCIS members. As we bring in a new year (and welcome a new collection of bad guys), here’s a list of the top 10 NCIS baddies.

#10 La Grenouille — Season 4

A French arms dealer and father of Tony’s girlfriend Jeanne, La Grenouille was not a violent man by nature. However, Director Shepard’s belief that La Grenouille killed her father put him in her crosshairs. “The Frog” was eventually found floating in the Washington Channel after being shot with the Director’s gun.

La Grenouille in NCIS Season 4

#9 Kyle Boone — Season 3

Boone was a serial killer that Gibbs put away early in his NCIS career. As the date of his execution approached, he offered Gibbs information on the location of his victims in exchange for a stay of execution. When Boone’s accomplice kidnapped Agent Cassidy, Gibbs decided that all deals were off and Boone had to pay the ultimate price for his crimes.

Kyle Boone in NCIS Season 3

#8 Michelle Lee — Season 6

Agent Lee used her position to steal classified information in an attempt to protect her sister. Her actions cost the lives of an NCIS agent and a Petty Officer. Choosing espionage when she could have gone to Gibbs for help makes her crimes particularly heinous. No wonder she gave Gibbs permission to kill her in order to get to “The Weatherman.”

Michelle Lee in NCIS Season 6

#7 Merton Bell — Season 7

Gibbs sent Bell to jail in Mexico. As retribution, Bell uncovered information linking Gibbs to the murder of Pedro Hernandez and partnered with Paloma Reynoso to bring Gibbs down. In the end, Paloma decided she was done with Bell and had him murdered during an ambush on Mike Franks.

Merton Mell in NCIS Season 7

#6 Chip Sterling — Season 3

In a case of serving revenge very cold, Sterling got a job in Abby’s lab years after Tony DiNozzo had been indirectly responsible for shutting down his old lab. After meticulously framing Tony for murder and going after Abby once she figured out what was going on, Chip got a transfer out of Abby’s lab and into prison. And Abby got her wish to always work alone.

Chip Sterling in NCIS Season 3

#5 Michael Rivkin — Season 6

Rivkin was a Mossad agent involved with Ziva on her father’s orders. Upon discovering Rivkin was spending his time in the US hunting down terrorists, Tony DiNozzo arrived at Ziva’s apartment to arrest him. After a scuffle, Tony shot and killed Rivkin. This was a turning point in the Tiva relationship that would take years to resolve.

Michael Rivkin in NCIS Season 6

#4 Mamoun Sharif — Season 4

This Lebanese terrorist gave Gibbs a dose of nerve gas before attempting to shoot him with his own weapon. Lt. Mann found the two in time to kill Sharif before he could harm Gibbs further. Gibbs recovered from the effects of the gas, but Sharif never came back from that bullet wound.

Mamoun Sharif in NCIS Season 4

#3 Jonas Cobb, “The Port-to-Port Killer” — Season 8

Cobb was a rogue ex-CIA operative who snapped. In the course of running amok, he killed Mike Franks, a man who had survived having his finger shot off and countless other baddies. Franks’ death was particularly poignant as he was terminally ill, and Cobb allowed Franks to go out fighting, the way he would have wanted.

Jonas Cobb in NCIS Season 8

#2 Paloma Reynosa — Season 7

Paloma wanted revenge on Gibbs for killing her father and swore she would make him work for her drug cartel or else kill everyone he loved. The fact that Papa Pedro killed Gibbs’ wife and daughter didn’t matter to her. After coming after Mike Franks, Gibbs’ father, and even Gibbs himself, Paloma was eventually — and mistakenly — gunned down by her own brother.

Paloma Reynosa in NCIS Season 7

#1 Ari Haswari — Season 2

Ari killed Kate. He came after Gibbs in his own basement. He fired at Abby. He shot Gerald. No other villain has gotten up close and personal with so many members of the NCIS team. That’s probably why it took his own half-sister (and future NCIS team member), Ziva, to take him out before he could kill Gibbs.

Ari Haswari – Season 2