Played by Tommy Wiseau
- Ate His Gun: Shoots himself in despair after he locks himself in the titular room and trashes the place.
- Betty and Veronica: The Betty to Mark's Veronica for Lisa's Archie
- Oh hai, X.
- That's the idea!
- "Don't worry about that/it." Says this to things people would typically worry about, with variations.
- Cold Ham: Thanks to Wiseau's horrible acting. Even when Johnny is screaming and going over the top, he sounds bored with his dialogue.
- Dull Surprise: "I did not hit her, it's not true. It's bullshit, I did not hit her! I did NAAAGHT... Oh hi, Mark."
- Eyes Always Shut: His eyes are usually halfway closed for whatever reason.
- Flowers of Romance: He buys roses for Lisa so much he's the flower shop's favourite customer.
- Gonk: Tommy Wiseau isn't as attractive as he thinks he is.
- The Hero: Or at least, this is what Wiseau conceived of him being.
- Hong Kong Dub: A lot of his lines obviously don't match up with his mouth movements.
- The Hyena: "Ts-Hahahahahahahahaha."
- Large Ham: Somehow manages to overlap this with Dull Surprise.
- Looks Like Cesare: Black hair, and an appearance that suggests he doesn't go outside much.
- Nice Guy: Lets see, he apparently buys Lisa a dozen red roses every time they make love, or at least often enough to be the flower shop lady's favorite customer, and would do anything for. He's paying for Denny's college and tuition without asking for anything in return. Is incredibly nice to all of his friends and seems to only want to make Lisa happy. . . From an objective point of view, there's really no logical reason for Lisa to cheat on him, or hate him the way she does.
- The Teetotaler: The exception being the Scotchka scene.
- Too Good for This Sinful Earth
- Took a Level in Jerkass: Towards the end of the movie, starting with the fight between him and Mark as he discovers that Lisa is cheating on him during his birthday party.
- Unstoppable Rage: The scene where Lisa leaves him, causing him to go into a rage and trash his entire apartment, including mustering the strength to throw a massive CRT television (those things are heavy!) straight out the window.
- What the Hell Is That Accent?: Especially funny since it's Tommy Wiseau's natural accent.
- You No Take Candle: Slips into this at times, most notably "Everybody betray me! I fed up with this world!"
Played by Juliette Danielle
- Beauty Is Bad: Gives this impression.
- Bitch in Sheep's Clothing: She seems nice, at first. Then we find out that she's cheating on her loving future spouse because she's bored with him.
- Brainless Beauty: Her schemes aren't very well thought out.
- "I don't want to talk about it"
- "Don't worry about it."
- Character Shilling: Many characters will stop whatever momentum the movie has in order to talk about how great Lisa is.
- The Chick: Right down to being in a Love Triangle with The Hero and The Lancer.
- Determinator: Juliette Danielle is, at least. Knowing all the abuse, degradation, and humiliation she endured while making the film, it's truly amazing that she got through it at all.
- Disproportionate Retribution: She's cheating on Johnny because she thinks he's boring.
- Dumb Blonde: In a way. Most notably not caring about the fact that if she continues cheating, she's going to destroy Johnny, despite Stevens serious words to her.
- Hello, Nurse!: Barely a scene goes by where someone doesn't comment on her attractiveness.
- Hot Girls Are Bitches: She's as pretty as she is reprehensible.
- Informed Attractiveness: Lisa's actress isn't ugly, but she still does not quite live up to how beautiful all the men act like she is.
- It's All About Me: Case in point, after her future spouse commits suicide, her first action is to tell the guy she was cheating on him with (who also happened to be his best friend) that they can finally be together. Mark rightfully calls her out on this.
- Jerkass: Cheats on her loving future spouse with his best friend because she's bored with him, was implied to have just been using him for money in the first place, lies about him abusing her to justify it and tells his best friend that there is nothing between them after Johnny kills himself. At the end, Mark finally grows a spine and tells her off for it.
- Manipulative Bitch: Dear God, Lisa. Mark flat-out lampshaded this.
- Pet the Dog: Despite her nastiness, Lisa seems to genuinely care for Denny.
- Satellite Love Interest: As the girlfriend, her scenes are limited to having sex and sitting on a pedestal. As the antagonist, she's the axis of the whole film.
- The Sociopath: Peter speculates that she is one based on her behaviour.
- Smug Snake: Sure Lisa, be all secretive and paper thin with your lies and cheating. Johnny will never find out.
- Stupid Evil: She makes quite a few mistakes during the movie.
- The Unfair Sex: Inverted; everyone acts like the affair is her fault while downplaying Mark's role. Though she was the one throwing it in people's faces.
- Your Cheating Heart: Cheating on Johnny with Mark.
Played by Greg Sestero
- Betty and Veronica: The Veronica to Johnny's Betty for Lisa's Archie
- Dull Surprise: His reaction every time Lisa invites him over "to talk" and then winds up trying to sleep with him. As he explained in The Disaster Artist, there was no way for Greg to make his performance seem convincing, so he didn't even try.
- Flat Character: Greg Sestero himself views Mark this way. According to him, any time he tried to add any depth to the role, Tommy would accuse him of trying to be king of the world.
- Four-Temperament Ensemble: The Phlegmatic.
- I'm a Man, I Can't Help It: The presumed explanation for The Unfair Sex below.
- Important Haircut: Subverted. He shaves his beard and everyone makes a big deal out of it, but it doesn't signal a change in character.
- The Lancer: He's Johnny's best friend.
- Marijuana Is LSD: Becomes uncharacteristically violent and belligerent after taking just a couple hits from a joint.
- Nobody Calls Me Chicken: CHEEP-CHEEP-CHEEP-CHEEP-CHEEEEEP!
- The Stoner: A hilariously ill-written variation. See Marijuana Is LSD above.
- Tuckerization: Attempted. According to The Disaster Artist, Tommy named Mark after the lead actor of The Talented Mr. Ripley "Mark Damon".
- The Unfair Sex: Inverted; everyone acts like the affair is entirely Lisa's fault.
Played by Philip Haldiman
- Ambiguous Disorder: His behavior is... incredibly bizarre for someone who is likely pushing his twenties. Even Tommy Wiseau has admitted the character makes more sense if you think of him as mildly retarded.
- Compressed Vice: His drug dealings with Chris-R are brought up once and then never again afterwards.
- Kid-Appeal Character: The only kid-like character in the movie (he is implied to be around the age of 18 but looks and acts much younger). Not that kids are even supposed to be seeing this movie, which is rated R, making him even more inexplicable.
- Man Child: To a degree. He keeps trying to go upstairs with Johnny and Lisa when he knows they're going to have sex, and presumably wants to join in, then follows them upstairs and jumps on the bed. He also talks about how he's "in love" with Lisa like a 7-year old, and fawns over her to a creepy effect.
- No Social Skills: "I just like to watch you guys."
- Phrase Catcher: "Oh hai, Denny!"
- Precision F-Strike: Against Claudette.
- Tagalong Kid: Denny doesn't have much importance to the plot.
Played by Carolyn Minnott
- Anger Born of Worry: She tears into Denny after she discovers that he was nearly killed by a drug dealer that he owed money to, though she seems to care for Denny's well being in the end.
- Audience Surrogate: Probably unintentional, but she asks questions the viewers are probably wondering, such as asking "What are these characters doing here?" when she walks in on Mike and Michelle making out, and asking Denny numerous questions about his relationship with Chris-R (none of which are ever answered).
- Brutal Honesty: She flat-out admits to Lisa that she hated her ex-husband who's Lisa's father.
- Gold Digger: She certainly believes that women should aspire to be this and more or less states that it's the only reason she married Lisa's father.
- She even mentioned how she tried to sponge off Johnny.
- Hypocritical Humour: She states in one sentence how much she dislikes men, and states in the next sentence that men and women exploit each other.
- The Mentor: The closest thing this movie has to one. Naturally, she's very bad at it.
- Only Sane Woman: She may be an immoral, self-absorbed hypochondriac, but she's also the only character in this movie who seems even remotely aware of how absurd the plot is.
- Pragmatic Villainy: She wants Lisa to marry and be faithful to Johnny so that she can live off a stable life with him. This ends up with an extreme case of Villain Has a Point: If Lisa had listened to her mother, it would have been for the better for everyone involved! Johnny wouldn't have committed suicide, he and Mark would still be friends, Danny would still receive college tuition, Lisa would, again, live a good life and the flower shop would still have their favourite customer.
- Straw Feminist: She has a very low opinion about men, but she's at least open-minded enough to know that women can also be manipulative.
- What Happened to the Mouse?: Her breast cancer. It comes up once, then is never mentioned again."They have cures for everything."
- Word of God confirms that she'll live through it.
Played by Scott Holmes (credited as Mike Holmes in the film, due to Wiseau forgetting the actor's name)
- Beta Couple: With Michelle.
- Blatant Lies: He had to run back into the apartment after being caught having sex with Michelle and get his ... book. (That is, his underwear.)
- Have I Mentioned I Am Sexually Active Today?: In one scene, he tells the rest of the guys he has to leave so he can make out with Michelle.
- Large Ham: He's no louder than the rest of the cast, but his exaggerated facial expressions and non-stop mugging have to be seen to be believed.
- Plucky Comic Relief
Played by Robyn Paris
- Beta Couple: With Mike.
- Chocolate of Romance: Which she feeds to Mike.
- Only Sane Woman: The most level-headed of the cast, along with Peter. She knows how destructive Lisa's infidelity is and tries to talk her out of it several times.
- Also the only character who doesn't say "don't worry about it" or "everything's going to be fine".
- And she's the only female character who seems to be a decent person.
Played by Dan Janjigian
- The Aggressive Drug Dealer: Aggressive both in how he talks and how he threatens people with weapons.
- Chandler's Law: He starts the first violent part of the movie.
- Cluster F-Bomb: "Where's my FUCKIN' MONEY DENNY?!"
- Gangsta Style: How he holds his gun.
- Giant Space Flea from Nowhere: He isn't even referenced until he shows up to try and get Denny to pay him. After that, he is never mentioned or referenced again.
- Hot-Blooded: Definitely not an even-tempered guy.
- Large Ham: According to The Disaster Artist, Dan gave what's considered the most passionate performance in the movie.
- No Indoor Voice: To be fair, he was outside when he was doing all his yelling. Though presumably being inside wouldn't have stopped him.
- Sir Swearsalot: All the dialogue in his one scene is a Cluster F-Bomb.
Played by Kyle Vogt
- Busman's Holiday: Is still "playing the psychologist" even when he's off-duty.
- Chuck Cunningham Syndrome: Mysteriously disappears midway through the movie, and is never mentioned again.
- Ignored Expert: Johnny asks him for some advice about his relationship, which he gives him (for free, even!) and then Johnny gets annoyed and doesn't follow it because he doesn't feel like it. He also tells Mark that he should lay off the drugs, which he doesn't do for the same reason. On top of that, he also (probably correctly) diagnoses Lisa as a sociopath, which doesn't go anywhere either.
- Only Sane Man: Even in real life.
- Remember the New Guy: Not as much as his replacement below, but he still comes out of nowhere without being properly introduced, halfway through the movie.
- Smart People Wear Glasses: The most highly educated character and also the only one in the male cast who wears glasses.
- What Happened to the Mouse?: His actor quit mid-movie, so he disappears and Steven takes his place.
Played by Greg Ellery
- Real Life Writes the Plot: He only exists because Peter's actor quit.
- "The Reason You Suck" Speech: He exists solely to give one of these.
- Remember the New Guy: An impossibly lazy example. With about 20 minutes left in the movie, a new character suddenly appears and becomes deeply involved in the plot. Presumably, we're not supposed to notice that he suddenly appeared from nowhere without an introduction. Word of God is that Steven is supposed to be a replacement for the psychologist character Peter (whose actor left the production), but the audience is given no hint of this; indeed, Steven looks nothing like Peter.
- Suspiciously Similar Substitute: Originally, Peter had Steven's role, but his actor quit during filming, leading to Steven's creation.
- A Dog Named "Dog": A Doggie named Doggie, specifically.
- As Himself: Tommy didn't notice him until during the middle of a take. Later, he would ask the dog's owner if it was a 'real thing', perhaps not convinced it was a real animal.
- Precious Puppy
Flower Shop Lady
- As Herself: The owner of the flower shop in real life (it has since closed). She was allowed to appear as herself, as Tommy didn't have any extras to spare for the scene.
- Failed a Spot Check: She fails to recognize Johnny until he takes off his sunglasses.
HaroldClaudette's brother (and Lisa's uncle), who wants her to give him a share of her house. Claudette is less than willing to do this.
Shirley HamiltonClaudette's friend, who wants to buy a new house. Claudette asks Johnny to help her with a down payment, only for him to tell her it's an awkward situation. She expected him to be more generous. The only character in the entire movie to have a surname, yet she's entirely offscreen.
- The Ghost: Along with Harold.