No matter when you're watching "Mi-5," the important thing to keep in mind is that you shouldn't get too attached to anyone. This is the kind of show where anyone can get bumped off at any time -- and rightly so, since it's not the safest industry these people have chosen. It's espionage. Think of this as a running list of the show's agent -- active, temporarily deactivated and permanently deactivated.
Harry is the head of the counter-terrorism department at MI-5, having formerly worked his way up through the department as a field officer. Stern and matter-of-fact, Harry has to contend not only with disputes between his employees and his superiors, but
also difficult matters of conscience, having to balance what is morally right and was is right for national security.
Portrayed by: Peter Firth
An Mi-6 agent and torture survivor initially brought in to handle the Tom Quinn assassination case, he has since emerged as team leader. Married to fellow agent Fiona, he possesses a no-nonsense demeanor and is more than capable of making unemotional and unpopular decisions for the good of the mission.
Portrayed by: Rupert Penry-Jonex.
Well-versed in the ways of technology, analyst Malcolm is the go-to guy when it comes to computer hacking, device tracking, surveillance setup, and the implementation of any number of spy gadgets.
Portrayed by: High Simon.
Zafar "Zaf" Younis .
Having previously worked with Adam Carter at Mi-6, Zaf was brought to Section D when Fiona and Danny were being held hostage. A Junior Case Officer and devout Muslim, he functions best as an undercover agent, able to infiltrate many sleeper cells.
Portrayed by: Raza Jaffrey
Joanna "Jo" Portman.
An aspiring journalist, Jo was so vital in helping Mi-5 capture Clive McTaggart's murderer during series four that Adam offered her a job at Section D. Starting as a Junior Case Officer in the field, she switched to help Malcolm with the tech side of things after Colin's untimely death.
Portrayed by: Miranda Raison
Rosalind "Ros" Myers.
Initially an Mi-6 officer, Ros joined Mi-5's ranks after helping them capture her own father, a powerful ambassador attempting a government coup. Headstrong and calculating, she is Section D's most dedicated staffer.
Portrayed by: Hermione Norris .
A Senior Case Officer and Chief of Section D, Tom joined government agency MI-5 in 1996 and separated himself quickly from the pack as a result of his cunning instincts, his firm leadership, his ability to excel under pressure, and his trust in the skills of his coworkers. After he is framed for the murder of an Air Chief Marshal, Tom was able to clear his name and return to work, only to be decommissioned for insubordination.
Portrayed by: Matthew Macfadyen.
A graduate of Oxford University, Zoe dedicated her life to her career as a Junior Case Officer at Section D. Skilled in undercover work, she was able to become somebody else with just the right amount of backstory, improvisational instincts, and honest-to-god charm. After being found guilty of involuntary manslaughter and conspiracy to murder, Mi-5 helped her flee to Chile, where she can live the rest of her life with her lover Will.
Portrayed by: Keeley Hawes.
A Senior Case Officer, Tessa joined MI-5 in the 1980s and excels best in intelligence-gathering missions. Idolized by teammate Zoe, Tessa nevertheless comes across as cold, calculating, and often combative. After being fired when discovered to have been running phantom agents, Tessa started her own private security firm. She was late seen betraying Mi-5 and fleeing the country.
Portrayed by: Jenny Agutter.
A Senior Intelligence Analyst, she split her time between Mi-5 and GCHQ (Government Communications Headquarters). After getting caught up in the Cotterdam scandal in series five, she fakes her own death in order to save Harry from imprisonment, escaping the country forever.
Portrayed by: Nicola Walker.
Young, headstrong , and financially unstable, Danny joined Section D as a Junior Case Officer in 2000. Proficient in the ways of surveillance and hand-to-hand combat, Danny was often the first point of contact despite his hotheadedness. In the last episode of the third series, Danny is executed, sacrificing his life for Fiona's.
Portrayed by: David Oyelowo.
An administrative officer in Section D and Danny's original flatmate, Helen is still adjusting to her new job at MI-5 when, on the series' second episode, she is asked to replace Zoe on a dangerous undercover mission. Despite showing some grace under pressure during the mission, she was quickly found out by MI-5's target and was tortured and murdered in front of Tom.
Portrayed by: Lisa Faulkner.
Adam's wife and fellow Mi-6 agent, she became a permanent member of Section D after Zoe's departure. In series four, alas, she was murdered by her vengeful ex-husband.
Portrayed by: Olga Sosnovka.
One Mi-5's best technical officers, Colin was caught spying on powerful conspirators and hanged to death in the series five premiere.
Portrayed by: Rory MacGregor.