- Played by: Fionn Whitehead
- Ambiguous Disorder: He clearly has some kind of mental disturbance, but its never made clear if it's an anxiety spectrum disorder (like OCD, paranoia) or if it's a personality disorder. This is because there's so much to it he has some illness that is almost specific to his situation and which can definitely be made worse by all the viewer's actions - and because it's slightly different in its appearance for each path you can take. Because you're probably meant to make it worse, it's tailored for the place Stefan's in.
- Cosmic Plaything: Comes to regard himself this way after he finds out / believes someone is controlling him.
- Ineffectual Loner: While coding his entire passion project by himself might maintain its artistic integrity, the demands required to make such an ambitious game like Bandersnatch work prove to be way too much for one young programmer to handle (months in, he can barely get the game to start) and most of the endings consist of him failing to finish it properly for one reason or another with one of them having Stefan outright dying from fatigue.
- Insane Equals Violent: It's near-impossible to get him out of Bandersnatch without having him experience serious Sanity Slippage and committing a horrific murder.
- Limited Social Circle: A rare example of this not occurring in a sitcom. Stefan seems to have no friends, and never interacts with anyone outside of the Bandersnatch staff or his dad. There's also no significant reason offered for this, either, which makes it a very straight example. He is obviously mentally ill, though, which could explain some of it, not to mention spending the duration of the story working his ass off on the game. It makes sense that people besides his coworkers, therapist, and the man he lives with wouldn't figure into his life much.
- Meaningful Name:
- Butler. He serves you, the viewer.
- Stefan may be after computer scientist Stefan Langerman, who invented the queap priority data queue — a system by which, when there are multiple data pathways, the "best" is automatically chosen; it also lets you add and remove arbitrary (pointless or looped) data pathways. It looks like the White Bear/pathways symbol but elides choice.
- Stefan shares the last name "Butler" with Mark Butler, one of the co-founders of Imagine Software, whose infamous real-life Vapor Ware project "Bandersnatch" inspired this film.
- Never My Fault: Once he starts to suspect it, he blames the alien force hovering over the periphery of his life for all his woes related to the game when many of the decisions available to the viewer are either broad or minor in consequence. Not once in any of his conscience attempts "to start over" does he ever consider asking for a little extra help from Colin or any of his other coworkers with the mammoth task he has burdened himself with.
- Self-Made Orphan: One of these murders, if he lives long enough, is always of Peter, his father. His mother is already dead, which makes him this. He also holds himself responsible for his mother's death, but we see that he couldn't ever have prevented that, no matter what happened.
- Played by: Craig Parkinson
- Fantasy-Forbidding Father: He wants his five year old boy to stop playing with stuffed animals.
- The Lost Lenore: Stefan's mother is this to him.
- My Beloved Smother: A rare male example — often interfering in Stefan's life, lying to him — but seems to act with good intentions. Generally.
- Overprotective Dad: Actually averted (probably). Peter is very protective of Stefan but, unless you go down the conspiracy route, he's completely right that Stefan is unstable and needs psychiatric help. The only way to avoid tragedy is to follow his advice.
- Standard '50s Father: Although set in England in the 1980s, Peter fulfills most of these tropes — being cold to his son and enforcing gender stereotypes, not liking the introduction of technology. Except in the paths where he's not Stefan's father, of course.
Dr. R. Haynes
- Played by: Alice Lowe
- Distaff Counterpart: A female R. Haynes in comparison to Rolo Haynes from a previous episode of Black Mirror, and this one can be just as evil as Rolo.
- There Are No Therapists: Averted, except if you choose to follow the path that turns her into a Psycho Therapist that is part of the conspiracy.
- The Shrink: Stefan's therapist, Dr. Haynes, may be the well-meaning but ineffective variant. While she seems to look out for Stefan and tries to talk him through his troubles, she fails to stop his Sanity Slippage. She also has some shades of the harmful variant, depending on her involvement in P.A.C.S. (if she is involved at all)
- Played by: Will Poulter
- Affluent Ascetic: Despite being a famous game designer who according to Mohan "made enough money this year to buy a Lamborghini", he still lives fairly modestly. His apartment is even shown to be in Trellick Tower, which at the time was one of London's most infamously crime-ridden social housing complexes.
- Alice Allusion: Colin is representative of the White Rabbit, from his physical appearance to his plot uses.
- Cloud Cuckoolander: In line with his being a Conspiracy Theorist, as explained below.
- Conspiracy Theorist: Colin believes even Pac-Man is part of a government conspiracy to control people. He might or might not be right.
- Dissonant Serenity: Most notably when Stefan asks him to kill himself. He does it without thinking twice.
- Dull Surprise: Isn't surprised or fazed by anything, including Stefan's breakdown, Stefan's order to kill himself, or Stefan's revelation that he killed his father.
- Erudite Stoner: A brilliant programmer and habitual drug-user.
- Face Death with Dignity: If Colin comes in to check in on Stefan after he murders his father and starts to bury the body, he casually asks if Stefan is going to kill him too. If Stefan says yes, he calmly states that a knife will sting, searches the room for a blunt object to be knocked unconscious with, hands it to Stefan, and holds still so Stefan can kill him quickly.
- Hipster: Doesn't approve of Stefan's taste in music, and makes him take down a list of his own favorite bands.
- Meaningful Name: Shares a surname with Jon Ritman, a real life legendary game designer from the 1980s.
- Medium Awareness: Seems to realize he's a fictional character in an interactive movie.
- Played by: Asim Chaudhry
- Asshole Victim: During the story path where Stefan kills his father, Mohan will visit him if Stefan says Bandersnatch won't be ready by the end of the day. Stefan ends up killing an angry, sarcastic Mohan off-camera after he discovers Mr. Butler's corpse in the middle of his rant.
- It's All About Me: During some endings, he seems far more concerned that his company is going out of business than the fact someone (Stefan's dad) got brutally murdered.
- Jerkass Has a Point: He's outwardly friendly and enthusiastic, yet very abrasive at times, especially when things aren't going his or Tuckersoft's way. But despite his rude behavior, he is right in being angry at Stefan for failing to deliver on his promise, as it is he who takes the blame from the investors if the company does not release the game on time.
- Naturalized Name: Variation; his surname Thakur is the basis for his company's name Tuckersoft.
- Pet the Dog: When Stefan didnt have enough time to finish Bandersnatch, he was understandable pissed, but he does give Stefan a bit more time to finish the game.
- Played by: Tallulah Haddon
- Played by: Laura Evelyn
- Disappeared Dad: There are some endings whereby Colin has disappeared for some reason or another, all as decided by the viewer.
- Legacy Character: Colin and Kitty's daughter.
- Tempting Fate:
- When she's a baby, Colin refers to her as "Daddy's little legacy". Next time we see her, she's exactly that.
- She decides to adapt the story Bandersnatch, even after it's already supposedly turned two people into insane murderers.
- Played by: Jeff Minter
The fictional author of the choose-your-own-adventure Door Stopper Bandersnatch, who is never seen, but whose shadow the entire story lives in. He is primarily famous for two reasons: writing unique and original sci-fi stories, of which Bandersnatch is one, and for going mad and murdering his wife.
- Actor Allusion: Davies is portrayed by Jeff Minter, an eccentric UK video game designer and possible template for characters like Stefan and Colin in Real Life
- Captain Ersatz: Sci-fi writer known for brilliant novels but goes insane? Never heard of him!
- Posthumous Character: The film takes place after Jerome has long since died.
- Sanity Slippage: Implied to be due to a pre-existing mental condition and LSD usage, a la Syd Barrett or Brian Wilson. Unlike them, however, he went violentlyinsane.
- Slasher Smile: You can "meet" him grinning down at you like this if you've got to the safe scene without letting Stefan talk about his mum, and enter the password "JFD". It's a Jump Scare.
- Played by: Fionn Whitehead
In some timelines, the actor playing Stefan.
- Cannot Tell Fiction from Reality: Whilst the character Stefan struggles with this in most stories you can choose for him, in the one that ends with it being revealed that Netflix are filming a fictional Bandersnatch and Stefan in being played by Mike, Mike does actually think he's Stefan, too, even at least for a moment — suggesting that the curse of recreating the story really will drive you to this point of insanity.
- Destination Defenestration: He attempts this, because he thinks he really is Stefan, and thinks that Stefan would have jumped out of a window rather than fought his therapist. It's this that gets the take cut, with him being very confused that he's on a film set.
- Lost in Character: Mike is playing Stefan in a film about... the film you could have been watching if you made a different choice... and loses it enough to be convinced that he is Stefan, even attempting to fight decisions.
- Tempting Fate: He's another guy signed on to retell the Bandersnatch story, and shows signs of going crazy.