Beware the Nice Ones: He can go from dashing and witty to deeply scary and holding a gun in Your face in a matter of seconds.
Bi the Way: Jack is attracted to men and women and anything in between, as well as non-humanoid aliens. It's stated in Doctor Who that in the 51st century almost every human is bisexual.
Body Horror: His body regenerates layer by layer, and pops him back into consciousness as soon as he's able to live again... even if his skin isn't done regenerating yet. He does a lot of screaming at times.
Broken Ace: As the series progresses, you definitely see that Jack is having trouble dealing with the shitload of angst he's gotten handed with him.
Brought Down to Normal: In the first episode of Miracle Day, he discovers that while the rest of the world has become The Ageless, he's now mortal again. He regains his immortality by the end of Miracle Day.
Cartright Curse: Granted, his immortality means he can't find a lifelong partner anyway, but as it turns out they have a habit of dying in messy ways (such as Estelle and Ianto). Alice's mother Lucretia was a rare lucky one, and even she grew to resent Jack for his eternal youth prior to her death of old age.
Chivalrous Pervert: Has the occasional flirt with Gwen (and jokingly invites her for a threesome) and has a snog with his ex-boyfriend shortly before he asks his sometime 'dance partner' Ianto on a date. Has been happily married at least once, and is still good friends with his ex-girlfriend from the 1940s, pretending to be his own son. Makes sure to spend quality time with his daughter and grandson and takes responsibility for them. The world is ending (again), he goes on a complete bender, gets smashed drunk, hooks up with a random bartender... and because he happens to be mortal that day (long story), he still insists on using condoms.
Cold-Blooded Torture: Was the Time Agencies top interrogator for 10 years. Considering other members included John Hart, and he is shown to do this on occasion, this is somewhat chilling.
Cursed with Awesome: After episode one of Miracle Day, it's clear how lucky he's been with his type of immortality.
Death by Origin Story: He was killed by Daleks on Doctor Who and was revived and made immortal by a temporarily god-like Rose Tyler. Every time he died subsequently, he then returned to life. When we meet him at the start of the series, his death and resurrection happened 138 years ago. His death, abandonment by the Doctor, and immortality, more or less created the Jack we see here.
Ethical Slut: For the most part, extremely ethical about it, to the point where if someone in a monogamous relationship kisses him, he probably won't kiss back. Jack probably could have seduced Gwen away from Rhys if he had really tried to, but instead he was the one telling her to keep some small measure of normality in her life. Despite his desire for Gwen to have a normal relationship with Rhys, he has cast her longing looks in the series.
Immortality Hurts: Especially if it's well within reason that he has died over a billion times. He was once buried alive. He suffocated to death and came back every few minutes for two thousand years. That's not the worst that's happened to him.
Leitmotif: "Captain Jack's Theme", a barnstorming (literally) action theme that also captures Jack's subtle mystique. According to Ben Foster, he wrote the theme around the phrase "here he comes in a ruddy great tractor", as the theme first plays when Jack... drives through a barn in a tractor.
Limited Wardrobe: Always wears some variation of a blue shirt, dark trousers held up by suspenders, brown boots and an RAF greatcoat. (When it's destroyed, Ianto finds a new one for him within a day while the world is ending.) While there was some variation in earlier series, his outfit goes completely unchanged for the duration of Miracle Day.
Mean Boss: His management style involves a lot of snapping and shouting at people who question him and he seems to consider explaining his more unpopular decisions to be a completely foreign concept (which is unfortunate, because he's almost always right).
Mr. Fanservice: He's the character most likely to get naked (which was also Lampshaded in Doctor Who). Finally gets a proper (and quite magnificent) sex scene in series 4.
Mr. Vice Guy: You'd think it would be his lust that gets him into trouble, but it's actually his brashness.
Mysterious Past: Other than his immediate family, birthplace, and former occupation, almost nothing is known about him. What is known normally isn't pretty.
No Name Given: "Jack Harkness" is not his real name, but one he stole from a World War II pilot and has used ever since.
Offing the Offspring: More specifically, Offing the Grand-Offspring. Not that he had much of a choice in the matter, though, especially after having crossed the Despair Event Horizonover Ianto's death previously.
Out of Time, Out of Mind: 1874 years of unending torture didn't seem to bother him too much. It is possible that he simply stayed dead for the duration of it, but it can't be known.
Alternate Character Interpretation is that every time he revives, so does his sanity. Never mind 1874 years of suffocate and revive, imagine how he can still possibly be sane after what the Master and the Toclafane must have done to him during the Year That Never Was.
Papa Wolf: Hurt his Team and you are in for a world of pain. The Doctor has mercy. He doesn't. This is best shown on two separate occasions: first when he tricks a Starfish Alien in human form that manipulated Tosh via sex and emotions into teleporting into the heart of the sun, and when his team was captured by cannibals and he performed a Big Damn Heroes with a tractor and a pump action shotgun. A Team Dad for many the same reasons.
Shell-Shocked Veteran: Has seen more pain and destruction than any other good-aligned character in the Whoniverse, except the Doctor and possibly Rory Williams. Becomes even more traumatised after the events of Children of Earth. Manages to weaponise that fact from the get-go in Miracle Day, when he's able to suggest experimenting on the horrifyingly gruesome victims of Miracle Day's consequences, without being halted by his own emotions.
The Slow Path: Has had to wait from 1869 to 2008 for the Doctor to fix his vortex manipulator, and again from 27 AD to 2009 (with many, many deaths).
Total Watson and general Audience Surrogate, Welsh Gwen joining Torchwood is where the series begins. Functions as The Chick and/or The Heart, so much so that a coked-up-alien-fish calls her on it. An identical relative of one Miss Gwyneth (as the Doctor gleefully tells her, a "spatial genetic multiplicity"), which may explain her talent for using resurrection gimmicks. Does not take crap from anyone.
The Masquerade Will Kill Your Dating Life: Nearly all the problems in her relationship with Rhys in the first series are a direct result of her being unable to talk about anything that happens to her in her job. Thanks to Jack's intervention this gets quite a bit better in series 2, though.
Na´ve Newcomer: In series 1, she freaked out over most of the stuff the other Torchwood members considered as normal as their morning coffee.
Shell-Shocked Veteran: By series 2, she can calmly ask a pedestrian if they've seen a blowfish driving a sports car in complete deadpan. By series 4, she's become just as casual about extreme danger as Jack, and freaks out newcomers by treating the end of the world like a game.
Abusive Parents: "Adam" hints that his mother wasn't very kind to him - he describes the day she kicked him out, when he was 16, as "the nicest thing you've ever done for me, Mum".
And I Must Scream: The worst part wasn't when he died, or when he was revived as a deathless, sentient zombie when Jack used one of the alien Resurrection Gloves on Owen. Or even when Owen discovered that his body, while immortal, was no longer able to digest food or heal injuries naturally, making him rather fragile. No, the worst came in "Exit Wounds", when Owen was trapped in the control room of the Turnmill Nuclear Power Plant and faced the decision to vent the radioactive steam from the overheating core through the room he was in, in a Heroic Sacrifice to save the plant from going into meltdown. As he told Tosh over radio, the fact that this body was already dead meant that he wouldn't die quickly from the massive dose of radioactivity but instead would be trapped inside his body while it was slowly being consumed by the radioactive waste shredding his cells. He shut off the radio before he vented the system as to spare Tosh having to listen to his screams... assuming he was still able to scream, that is.
Anything That Moves: Has a penchant for suggesting wild sex any time the world's about to end. Once propositioned Ianto and Tosh when he thought they only had a few minutes left to live. Spends a lot of time trying to find new Fuck Buddies as well as one night stands.
Bi the Way: Hypnotizes a woman using alien pheremones in his first appearance, until her boyfriend shows up... at which point he promptly hypnotizes him too.
Break the Cutie: Starts the series completely broken, with no sign of "cutie" left. Gradually works his way back up, only to be broken over and over again. Eventually, we catch a glimpse of what he was like before Torchwood, and it turns out that he was a genuine cutie indeed. (In fact, Adam's interpretation of him wasn't even that far off.)
Killed Off for Real: Hard to tell how having his type of immortality reacts with his body being atomized. But for all intents and purposes, yes. By the end of Miracle Day, he's probably very definitely dead.
Our Liches Are Different / Our Zombies Are Different: Take you pick as to which he is. He becomes either a non-magical lich or a revenant zombie. Seems to be closer to lichdom than zombiedom as his mind is about as unaffected as it can be after coming back from the dead.
Pet the Dog: Owen's introduction was date rape — he used alien pheromones to make two people uncontrollably attracted to him. Two episodes later, he gets to experience the feelings of a woman being raped through telepathy, and promptly does a complete Heel-Face Turn on the issue. In the episode "Out of Time", he actually falls in love with someone, is dumped days later, and as a result (and after a period of violent mourning) generally becomes a nicer person.
Rape Is a Special Kind of Evil: His first episode saw him committing date rape on two people. Just a few episodes later, he got to experience rape from the other side through a telepathy gizmo, which gave him rather a lot to think about.
Red Right Hand: Evoked when he breaks his own little finger in an act of defiance. Since it can't heal, he wears one black leather glove from that point on.
Token Evil Teammate: Starts out as this in series 1 — first by raping two people in the very first episode, then by starting an affair with Gwen, who's in a monogamous relationship and uses him to cheat on Rhys. The first series has him slowly working his way towards a Heel-Face Turn, an arc that properly kicks into gear in series 2.
Too Spicy For Yog Sogoth: After he turns undead, Weevils are scared shitless of him, to the point they worship him like he was a god. He eventually gets Genre Savvy to this and weaponizes it.
Death personified also avoids him like the plague (he's already dead and there's nothing for it to feed on), and the Nostrovites (carnivorous shape-shifters) won't touch him because he "smelled a bit off."
Trauma Conga Line: Gets a new trauma every couple of episodes. Starts out broken, breaks more throughout series 1 and eventually kills Jack. Breaks again in series 2 and becomes a suicidal zombie.
Ascended Extra: Was only meant to have her small role in Doctor Who, then RTD transferred her character to Torchwood (even justifying why she'd been a medic there rather than a tech expert). It all payed off handsomely.
Beware the Nice Ones: Her plan to get the team into the Pharm has Ianto calling her "warped on the inside". She responds by smiling happily.
Boxed Crook: Because she stole plans for a superweapon - and handed them over to terrorists holding her mother - she was due to be held without charge by UNIT until Hell froze over. Because the plans were flawed and she still made them work, Torchwood got very interested.
Broken Bird: Was tortured by terrorists, and subsequently tortured by UNIT for seemingly cooperating with terrorists, before Jack rescued her and offered her a job.
I clear up your shit. No questions asked and that's the way you like it. When did you last ask me anything about my life?
Played by: Gareth David Lloyd (2006-09)
The Ensemble Darkhorse, due to much fan noise early on in the series. Responsible for getting the Torchwood team where they need to be, Ianto also can make a mean coffee and looks great in a suit. Started out as The Big Guy, but eventually was revealed to have a Dark and Troubled Past in his own right. Was initially part of Torchwood London and witnessed the Battle Of Canary Wharf. Becomes Jack's fuckbuddy after a while, and his exclusive boyfriend in series 2. Gets to meet the Doctor.
Ascended Extra: Gained more prominence in later episodes than earlier.
Bi the Way: Starts having sex with Jack halfway through series 1. They properly begin dating and become romantic in series 2. Doesn't openly identify as bisexual: it's "just Jack". (He does identify as bisexual in the novels, so that's either Depending on the Writer, or simply because Ianto lies a lot.) Feels comfortable with being Jack's boyfriend in the context of Torchwood, but quite uncomfortable with it around his family.
Noodle Incident: We never found out how he and Jack first started "dabbling".
Relationship Upgrade: He goes from loathing Jack to inexplicably shagging him in series one. Series two builds on the "relationship" part, with them agreeing on an actual date in the first episode. He comes out to his family in Children Of Earth.
Badass Normal: Eventually, not only does he become surprisingly desensitized to the weirdness around him, he's even willing to stand up to some of the freakier aliens. He even scares the shit out of Oswald Danes in series 4.
Back from the DeadAfter being stabbed to death by Bilis Manger in the series 1 finale, he was brought back to life via the Rift after it was opened and time was re-wound, thus preventing his death from taking place in the first place.
Berserk Button: He is shlubbish, out of shape, even a little dim sometimes. He's not in Jack's league, and he knows it. Gwen loves him anyway. Don't hurt her, or the secret conspiracy keeping Britain safe from alien invasion? It won't have the resources or ability to save you.
What Happened to the Mouse?: Despite Gwen suggesting that she get a job with Torchwood in Children of Earth, Lois is nowhere to be seen in Miracle Day. Admittedly, Torchwood is officially defunct after Children of Earth.
Played by: Lucy Cohu (2009)
A perfectly normal middle-aged woman with a perfectly normal young son, Steven. Spent much of her life in the witness protection program. Tries to cope with Jack, her father, as best as she can.
However, this wasn't entirely out of left field. Jack reveals he's been in relationships numerous times before (and we even get to meet some of these people), and he mentions how painful he finds it that he can't age while they will, so the CoE reveals did come with some hefty foreshadowing.
What Happened to the Mouse?: He's never captured or killed, simply disappearing after Abaddon is released and later defeated. As such, it's very likely that he's still out there and biding his time in another time period.
Captain John Hart
Here's what's going to happen: everything you love, everything you treasure, will die. I'm gonna tear your world apart, Captain Jack Harkness, piece by piece. Starting now.
Jack's former boyfriend of five years, also from the 51st century. A member of the Time Police, and — like Jack used to be before meeting the Doctor — a bit of a con man. Has a flair for the dramatic and wears cowboy gear for no discernable reason. Also shares Jack's love for standing on top of buildings.
Serial Numbers Filed Off: Of Jack himself, right down to his incredibly anachronistic wardrobe, being a rogue ex-Time Agent and his chosen name being an alias, that he adopted simply to parody Jack's own.
The Scapegoat: Is blatantly used by Prime Minister Brian Green to take the hit for his morally reprehensible actions.
You Look Familiar: Previously played Lucius Caecilius lucundus in "The Fires of Pompeii". RTD has stated he that he's probably a descendant and he considers the death of Frobisher's family to be the universe balancing itself out for the Doctor saving Caecilius' family.
Capaldi would also later go on to play the Twelfth Doctor, which according to Word of God will be addressed.