Supervisory Special Agent Jack Garrett
Leader of the IRT, he leads the team in its cases involving crimes that target Americans outside the US.
- Action Dad: FBI Agent with six kids. Don't mess with his son, Ryan, who's a cop...even when he's undercover during one of Jack's missions.
- Da Chief: He's the head of the IRT.
- Experienced Protagonist: He's an experienced FBI Agent. He's so well-known in the international law enforcement community that on certain occasions, he's allowed to carry his sidearm in countries that forbid firearms.
- Omniglot: Speaks a variety of languages, including Japanese, Spanish, etc.
- White Male Lead: Jack's the main character, the boss and the only white male member of the IRT.
- Weapon of Choice: Uses a railed SIG-Sauer P226.
- What the Hell, Hero?: He gets called out by his son, Ryan, for pulling him out of his undercover op in Tijuana, Mexico because the bikers can get wind of his FBI status if he doesn't show up sooner than later.
Supervisory Special Agent Clara Seger
- Experienced Protagonist: She's an experienced FBI agent, even before she left the bureau.
- Fair Cop: She's played by Alana de la Garza.
- Omniglot: Clara speaks Thai and apparently other languages.
- It's Personal: In "Type A," there was a cold case that involved the death of one of her friends when she was still working under the UN.
- Married to the Job: So much that Mae tries to get her to socialize with other people.
- Mr. Exposition: She's there to help the team learn what to expect in working in a different country in terms of what to do to avoid any Culture Clash problems.
- Weapon of Choice: Uses a Glock 17. She later switches to a Glock 34.
Special Operations Agent Matthew "Matt" Simmons
- Action Dad: He's the father of two boys and twin girls, and a badass who can take down suspects.
- But Not Too Foreign/Mixed Race: His features and name suggests that he's biracial, given that he's of Asian-American origin.
- "Pretty Like Me" confirms that he's Korean-American. Part of the episode is Matt arriving in Seoul to track down his missing grandmother.
- Experienced Protagonist: He's an experienced FBI agent who used to be with the US Army.
- Fair Cop: He's played by Daniel Henney.
- Omniglot: Can speak Arabic, English, Korean and Spanish.
- Weapon of Choice: Uses a railed SIG-Sauer P226.
Technical Analyst Russ "Monty" Montgomery
- The Face: Since the team is usually in another country, it's also Monty's job to speak with victims' family.
- Mr. Exposition: Helps fill in the team in on information regarding the victims and basic info on a country, sharing this role with Seger.
- Voice with an Internet Connection: Talks like this with the team from FBI HQ since he's not always in the field with them.
- Playful Hacker: Does this when time is running out. Not all jurisdictions like this approach.
Medical Examiner Mae Jarvis
- The Determinator: She won't let rules/cultural barriers hinder her job in examining corpses at all.
- Freeze-Frame Bonus: If you pay attention to closeup of him in the screen, you can see his full name on his badge.
- Omniglot: Speaks English and Thai.
- Hunting the Most Dangerous Game: What he's doing in "The Harmful One," more than just killing.
- Meaningful Name: Means "brave" in Thai.
- Woobie, Destroyer of Worlds: He's the Last of His Kind of his entire family, desperately driven to — in his mind — find worthy sacrifices for their spirits. And in the end, while he's successfully convinced to stop, he's nonetheless Driven to Suicide — all while lamenting that he'll be Dying Alone.
- Dirty Cop: Well, more like a resort dirty security guard. It helps him find victims.
- Freudian Excuse: He became a Serial Killer after his son died in an earthquake and another boy on vacation survived.
- Misplaced Retribution: He wanted to kill the young tourist boy who survived the earthquake instead of his son out of anger, but was unable to, so now he just settles for killing the eldest sons of any vacationing family he finds.
- All of the Other Reindeer: Samraj feels this way since he was in a bad caste, even though it was officially outlawed by the Indian government.
- Alliterative Name: Samraj Sabah
- Tragic Villain: Samraj wanted to ease his father of his pain in the afterlife, but he did it by killing his victims and getting their organs.
Natalie Knox & Nick Jamison
- Freudian Excuse: Natalie was raped as a nine year old by her stepfather but no one believed her. Years later, while living in Cuba, she was raped by an American tourist; that did not do good things to her psyche.
- Love Makes You Evil: Nick
Tuareg Brothers Amajagh, Ben, and Cadi
- Freudian Trio: Amajagh is the Id, Ben is the Ego, and Cadi is the Super Ego.
- Near-Villain Victory: She kills almost all of her targets and kills herself to prevent the IRT from finding her final victim, who she Buried Alive, but they manage to save him anyway.
- Revenge Before Reason
- Misplaced Retribution: Her husband was part of a group of protesters during the Arab Springs protests, and the group she was with was gassed by the police, which left him severely disabled and ultimately Driven to Suicide. So she blamed the other protesters and got to work killing them with the same gas.
Abu Hakim Al Badi & Marion Codwell
- Brainwashed and Crazy: Try to brainwash teenage girls into becoming suicide bombers.
- Hoist by Their Own Petard/Too Dumb to Live: They tell one of their victims all about themselves and their operation because they were convinced she'd die for their cause. Instead, she ultimately gives the police everything they need to shut them down.
- Middle Eastern Terrorists: Al Badi is based in Iraq. But it's never mentioned if he was with ISIS or an ISIS-affiliated terrorist group.
- Western Terrorists: Marion is former British MI6.
- Hikikomori: Is explicitly declared this in his IRT profile, and has the reclusive lifestyle — complete with a Hacker Cave — to back it up.
- Weapon of Choice: Uses an antique World War II-era Nambu Type 14.
- You Killed My Father: Blames his victims for ruining his family and consequently making them get Driven to Suicide.
- From Camouflage to Criminal: After he got discharged from the South African military in the 1990s, he began to target anyone involved in Pretorius, OSS' former black ops unit.
- Wolverine Claws: Uses them to torture and stage his victims post-mortem.
- Would Hit a Girl: Would be willing to hurt females if it needs to be done.
Deputy Director Walter Atwood
- Dirty Cop: All of his murders are to hide that he is part of a child trafficking ring.
- Killer Cop: He arranges numerous people to be killed to cover up his own corruption.
- Beard of Evil
- The Corrupter: He used his manipulations to turn a Russian nationalist prison guard into his accomplice.
- It's Personal: With Garrett, who helped put him in prison.
- The Red Baron: Known as The Ripper of Riga for using a biting device he invented to mutilate his unfortunate victims.
- Torture Technician: He used to be one during his time with the KGB, but after the fall of the Soviet Union he turned to being a Serial Killer to get his kicks.