Sergeant John PorterPlayed by: Richard Armitage
- Defiant to the End: His last words aren't just a profanity-laced tirade against his captors, but also a code that Scott is able to interpret warning about Project Dawn.
- Killed Off for Real: Very early on by Latif's followers.
- Plot-Triggering Death: Which results in Section 20 recruiting Damien Scott.
Sergeant Michael StonebridgePlayed by: Philip Winchester
- Beware the Nice Ones: Michael seems pretty even-keeled, but don't give him a reason to kill you.
- Broken Ace: A level-headed, consummately-professional SAS soldier who cheats on his wife with Kate and lets things get way too personal.
- Dented Iron: Sometimes has to fight through debilitating injuries.
- Determinator: Lots of things get in his way over the course of the series. Few of them stay in his way for long.
- Mr. Fanservice: Often seen with his shirt off.
- It's Personal: He lets things get to him. Of course, the murder of his wife would get to anyone, but the list doesn't end there.
- Stuffy Brit: Comes off this way sometimes, especially in comparison to Scott, but has a pretty sharp sense of humor underneath. His patience also has its limits.Scott: Oh, yeah, he's not gay. He's British. Easy mistake to make.Stonebridge: Fuck you.
- Vitriolic Best Buds: With Scott
- We Used to Be Friends: With Craig Hansen
- Your Cheating Heart: With Kate Marshall.
Sergeant Damien ScottPlayed by: Sullivan Stapleton
- Badass and Child Duo: Spends a significant portion of the hotel siege protecting a little girl, including making sure she doesn't see her father's bullet-riddled body.
- Beware the Silly Ones: Scott is an irreverent smartass who also happens to by extremely competent and lethal in the field.
- Chivalrous Pervert: Scott is surprisingly sensitive to women for a guy who screws his way around the world.
- Dark and Troubled Past: Stonebridge recruits him in Jakarta, where Scott is the loser in rigged prize fights for a local gang lord. He used to be a member of Delta Force, but was framed for drug possession and dishonorably discharged from the US Army after he started asking too many questions about a joint US/British/Pakistani operation in Iraq. Afterwards, he did some dirty work for the CIA for a while before becoming disillusioned with it.Scott: When I got back, they found ten keys of coke in my locker.Stonebridge: So you got what you deserved.
- Everyone Has Standards: Will happily bang just about anyone with a two X-chromosomes, but gives Stonebridge a solid What the Hell, Hero? about his extramarital affair.
- Hidden Depths: Amongst other things, he has a nearly eidetic memory, enough that (with some difficulty) he's able to repeat a very long hacking code sequence that he was only able to briefly glance at. Even more impressive considering that he "doesn't speak Geek."
- Really Gets Around: To the point that Sullivan Stapleton was getting tired of it.
- Sir Swears-a-Lot: "Fuck me!" is practically his Catchphrase.
- Token Minority: An American ex-Delta shooter on a British black ops team.
- Two First Names: "Damien" and "Scott".
- Vitriolic Best Buds: With Stonebridge
- Would Not Hurt A Child: Not on purpose, anyway. The accidental death of a target's son during his time with the CIA weighs heavily on him
Sergeant Julia RichmondPlayed by: Michelle Lukes
- Action Girl: Can be very handy in combat when she needs to.
- Ms. Fanservice: Usually downplayed (though she certainly makes British Army camo fatigues look good), but missions in Somalia and Colombia feature her in a bikini and short skirt, respectively.
- Mission Control: Her usual role in the Crib. She can put rounds on target when the need arises, too.
Major Hugh CollinsonPlayed by: Andrew Lincoln
Colonel Eleanor GrantPlayed by: Amanda Mealing
- The Atoner: She planned and led the joint operation that ruined Damien Scott's career and much of his life. When circumstances lead her to recruit him into Section 20, it eventually becomes clear that she wants to make it right.
- Big Damn Heroes: Rescuing Scott from a Nigerian hospital, despite being the only white woman in the building and multiple armed guards in the way.
- Colonel Badass: Though she usually runs things from the Crib, when she feels the need to handle something herself, she proves quite adept at sneaking in, blending in, killing somebody who needs to die, and disappearing again.
- Death Equals Redemption: Though Scott tries hard to save her, she kills herself and Latif by detonating an explosive in her pocket.
- I Did What I Had to Do: Trojan Horse, and Scott's career being destroyed.
- Two First Names: "Eleanor" and "Grant".
Major Rachel DaltonPlayed by: Rhona Mitra
- Determinator: The woman does not give up.
- Like You Would Really Do It: It looks like she's going to end up the same as Colonel Grant when Knox shoots her, but she survives. Then she gets Killed Off for Real halfway through the next season.
- Sanity Slippage: Becomes increasingly obsessive after the death of Sergeant Baxter.
- Worst Aid: Patches her own obviously-painful wounds in a filthy hideout in Beirut.
Major Oliver SinclairPlayed by: Rhashan Stone
- Black and Nerdy: Possesses a surprising level of hacking skill.
- Death Is Dramatic: His execution by ex-Apartheid mercenaries working for Knox is truly heartbreaking. Richmond empties a whole extra magazine into the guy who did it.
- Non-Action Guy: Averted. When Latif's henchmen find the Crib, Sinclair saves Richmond and shoots some bad guys.
- Number Two: To Grant and later Dalton.
Captain Kate MarshallPlayed by: Eva Brithistle
- Action Girl: Her primary role is trigger-puller and assault team leader.
- Fighting Irish: From Ulster. Connelly has some things to say about that. Kates not terribly concerned with the opinion of a terrorist-for-hire whose body count consists mostly of his fellow Irishmen.
- Killed Off for Real: By Connelly, despite his promising otherwise.
- Two First Names: "Kate" and "Marshall".
- Your Cheating Heart: Having an affair with Stonebridge. Not only is he married, theyre in the same unit, shes an officer and hes enlisted, and shes his team leader.
LatifPlayed by: Jimi Mistry
- Bad Boss: He'll keep you alive as long as you're useful. After that...
- Big Bad
- The Chessmaster: Repeatedly orchestrates decoy terrorist attacks in such a way that the response works in his favor. His plans also have multiple redundancies and backups in the event of a Spanner in the Works like Stonebridge and Scott.
- Magnificent Bastard: Quietly charismatic and utterly ruthless.
- The Mole: Impersonates an ISI officer sent to assist Section 20 in order to infiltrate the Crib. It helps that he's former ISI himself.
Mahmoud/ Dr. Iman Zuhari, PhDPlayed by: Sasha Behar
A British national who formerly fed WMD secrets to the Pakistani ISI. She claims to be the wife of the spy to try to stay under the radar, but Latif knows who she really is. She wants to surrender to MI-6 in exchange for protection from Latif.
- Chekhov's Gunman: The attractive English/Middle Eastern woman who brushes off Scott at the hotel bar turns out to be the spy he and Stonebridge are there to extract. And the one the terrorists in the hotel are after.
- Damsel in Distress: She's a spy in the "left state secrets in a trash can for someone to find" sense, as opposed to the James Bond variety. She panics when things get violent and is generally no help at all to the men trying to keep her alive.
- He Knows Too Much: Latif wants Mahmoud's information about Trojan Horse, and intends to ensure nobody else can find that information afterwards. He succeeds on both counts.
- Hot Scientist: A very attractive woman who used to do high-level work in the WMD field.
- Kick the Dog: Section 20 inadvertently hands her over to Latif, who interrogated her and leaves her dead on the side of the road.
CrawfordPlayed by: Iain Glen
- Death Equals Redemption: In his daughter's eyes apparently. He and Stonebridge are able to rescue her, but he dies in her arms.
- Evil Parents Want Good Kids: He sells arms to African warlords. His daughter is a doctor who cares for the victims of those warlords. He's pretty much dead to her as far as she's concerned, but Crawford loves his daughter nonetheless and is genuinely proud of her.
- Fallen Hero: Formerly an officer in the Royal Marines, now an unscrupulous international arms dealer.
- I Have Your Daughter: Agrees to give Section 20 all the information he has on Latif in exchange for their help rescuing his daughter from a Sudanese warlord.
- Papa Wolf: His daughter may despise him, but he'll still go to war to keep her safe.
Daniel ConnellyPlayed by: Liam Cunningham
- Hero Killer: Responsible for the death of Captain Kate Marshall.
- I Lied: Has a history of pulling this.
- Laser-Guided Karma: Section 20 hunts him down, and Grant herself shoots him in the face.
- Western Terrorists: Former IRA, now freelancing for the highest bidder.
HasaniPlayed by: Mel Raidio
- Balkanize Me: An Islamic Kosovar Albanian mob boss and drug dealer who runs a criminal empire in Albania and has some corrupt KFOR peacekeepers in his pocket.
- I Lied: Intends to kill his hostages after their ransom money comes in. Except for the young Dutch woman, who will be forced into sex slavery.
- You Have Failed Me: Latif is not happy with the attention Hasani's actions have attracted, though he doesn't seem to like him much anyway.
Conrad KnoxPlayed by: Charles Dance
- The Atoner: Knox is actually English, but his father was a banker for the South African Apartheid regime. His deepest motivation is to do right by all of the people in Africa to make up for it.
- Axe-Crazy: The end result of his Sanity Slippage. Knox decides to give his nuclear warheads to a Congolese terrorist group, then tries to nuke Johannesburg when that fails.
- My God, What Have I Done?: His reaction after he has his men assassinate his Walter Lutulu. This leads to his Sanity Slippage and eventual Villainous Breakdown.
- Well-Intentioned Extremist: His ultimate goal is to unite most, if not all, of Africa under one flag. This unified African nation would be (in his hopes, at least) a world superpower whose people enjoy safety, prosperity, and a high standard of living.
Craig HansonPlayed by: Shane Taylor
- Fallen Hero: Former SAS operator turned murderer, terrorist, and Psycho for Hire.
- It's Personal: Due to the incident with his little brother.
- Never My Fault: Pulled a You Owe Me on Stonebridge to convince him to push his little brother through SAS Selection against Michael's better judgement. When his brother, a Shell-Shocked Veteran with a drug addiction, suffers a psychotic break during a live-fire exercise and starts shooting his teammates, Michael has to kill him to protect the others. Hanson blames Stonebridge and murders his wife as revenge.
- Psycho for Hire: Offers his services to Conrad Knox, quickly proving that no job is too dirty.
- We Used to Be Friends: Served with Stonebridge in Iraq, and saved his life at one point.
Karl MatlockPlayed by: Vincent Reagan
- The Atoner: He regrets having taken part in UN peacekeeping missions during his time as a Legionnaire, since they didn't actually help anyone and at best only delayed the violence they were ostensibly there to stop. As disillusioned as he is, he believes in Knox's vision of a United Africa.
- Intergenerational Friendship: With the much-younger Jessica Kohl. Exactly how close they are is unclear, but he trusts her with his life and she's comfortable being topless around him.
- Noble Demon: He's a mercenary willing to kill if he must, but he's working for Knox out of idealism, doesn't care for vendettas, tries to avoid any unnecessary violence, and when taking a young child and his mother hostage, tries to shield them from violence and treats them as well as he can, even going out of his way to let the kid play soccer on a World Cup field.
- Not What I Signed on For: Refuses to go along with it when post-Villainous Breakdown Knox decides to just start nuking cities. Unfortunately, Hanson enforces the Resignations Not Accepted policy.
- Old Soldier: An American veteran of the French Foreign Legion, highly-decorated at that.
- Token Good Team Mate: Follows Knox because he believes in his vision and wants to apply his skills to do some good in the world.
Jessica KohlPlayed by: Natalie Becker
- Cold Sniper
- Dark Action Girl: Beautiful and deadly.
- Intergenerational Friendship: Although it's unclear if they are a couple or Just Friends, she's very close to Matlock, who is significantly older.
- Ms. Fanservice: Is perfectly comfortable letting Matlock (and the audience) see her topless.
Rebekah LevyPlayed by: Lyne Renee
- Badass Israeli: Mossad assassin
- Dark Action Girl: Utterly loyal to her country, to the point of murdering innocent people if she thinks it's necessary to get to her target. Her Establishing Character Moment is when she kills a poor airport security monitor to gain access to his system.
- HeelFace Turn: In Shadow Warfare
- Killed Off for Real: In Shadow Warfare
Christy BryantPlayed by: Stephanie Vogt
- Femme Fatale
- The Man Behind the Man: She "suggests" several of Knox's moves, most notably the assassination of Walter Lutulu.
- Rogue Agent: A CIA field officer in Africa who assisting Knox. It turns out the CIA was not supporting Knox and was only interested in recovering the stolen nuclear warheads. Langley disavows her once they realize what she's been up to.
- We Used to Be Friends: Was Scott's handler when he did wetwork for the CIA, while also having an affair with him. She claims the affair was genuine, while Scott bitterly describes it as "A couple of killers fucking between marks." Nevertheless, she's still able to manipulate Scott through his attraction to her.
Walter LutuluPlayed by: Eamonn Walker
Leo KamaliPlayed by: Zubin Varla
- Double Reverse Quadruple Agent
- Family Man: He may be the world's top terrorist, but he loves his daughter. Mess with Ester and you're dead— or worse.
- Family Values Villain
- Beard of Evil: He shaves it off after he fakes his own death.
- Bald of Evil
- Badass Baritone: And how.
- Evil Sounds Deep
- Evil Sounds Raspy
- The Man in Front of the Man: The entirety of Shadow Warfare sets him up as the potentially back-stabbing crony of terrorist mastermind Al-Zuhari, only to reveal that Al-Zuhari has been dead for years, with Kamali carrying out all of his work alongside maintaining an image of Al-Zuhari's still being alive.
James LeatherbyPlayed by: Dougray Scott
- Axe-Crazy: "Violent and unstable" would be an understatement.
- Brave Scot: Not so much brave as psychotic, but hes immensely proud of his Scottish Heritage. Stonebridge quickly starts calling him Braveheart just to piss him off.
- Depraved Homosexual: His monologue during his sex scene makes it clear just how sadistic and racist he is. Each successive scene sees him more violent and unhinged.
- Fallen Hero: Former SAS, now a terrorist for hire.
- Green-Eyed Monster: He thinks his boyfriend might have cheated on him. How does he react? He shoots his boyfriend through the hand, then shoots the guy who Leatherby thinks he might have cheated with.
- Hypocrite: Blatantly hits on Stonebridge, then tortures his own boyfriend on the mere suspicion of infidelity.