The Big Bang Theory/Characters

Significant characters on The Big Bang Theory, and their associated tropes.

Leonard Hofstadter, Ph.D. (Johnny Galecki)
"We're all responsible, I say we all go [apologize]. Come on, who's with me? ...Free comic books to anyone who comes with me! ...I might get punched, you really wanna miss that?"

Ostensibly the main character, Leonard is the most normal of the guys by having no outlandish quirks and generally operates as the Only Sane Man. He (and his friends) work at Cal Tech, his field being in Experimental Physics. He has lived with Sheldon since late 2002 and is his best friend, though Sheldon's quirks annoy him to no end. He instantly gained a crush on Penny when she moved into the apartment across the hall and much of the show is about how they both change from interacting with each other. - "Penny: (to Sheldon) Leonard and I are in a relationship, and occasionally we're gonna fight. But no matter what happens between us, we will always love you. Right, Leonard?
 * Abusive Parents: His mother is an iceberg of a woman who has never shown him any affection or approval.
 * Better As Friends: His relationship with Penny goes back and forth from this. Even though things are less complicated when they aren't together, there is no denying their attraction to each other.
 * Blind Without'Em
 * Butt Monkey: At times.
 * Crazy Jealous Guy: Played for drama as much as laughs.
 * Deadpan Snarker: Around Sheldon, at least.
 * Dogged Nice Guy: He could provide a trope image, spending the first two seasons pining after Penny.
 * Embarrassing First Name: He mentions that he doesn't like the name Leonard because it ends in the syllable "-nerd".
 * Embarrassing Middle Name: Leonard Leakey Hofstadter. (It has nothing to do with his history of bed wetting.)
 * Even the Guys Want Him: When Leonard demostrates to Raj how he can be more popular with girls by being more confident (and removing his glasses). Raj is mesmerized by it.
 * Hollywood Dateless: At times, though it has been made pretty clear that interacting with Penny has greatly improved his dating life (even outside of Penny herself).
 * Hollywood Nerd
 * Innocently Insensitive: Has a serious intellectual snobbery problem. Of course he doesn't realize it.
 * Lovable Nerd
 * Love Interest: For Penny, thus providing much of the show's plot impetus.
 * Masculine Girl, Feminine Boy: Feminine Boy to Penny's Masculine Girl.
 * Meaningful Name: Named for television producer Sheldon Leonard, anthropologist Louis Leakey, and the Hofstadters (Richard, Douglas, etc.).
 * Megane
 * Nerd
 * Official Couple: With Penny, as it is pretty clear they are the main romantic relationship of the series.
 * Only Sane Man: The sanest of the four main guys, at least.
 * Smart People Play Chess: He plays and in a season 5 episode teaches Penny to play.
 * Smart People Wear Glasses
 * Shipper On Deck: Clearly supports Howard/Bernadette and Sheldon/Amy.
 * Team Dad: Despite his snarkiness, Leonard increasingly becomes this throughout the series, particularly towards Sheldon.

Leonard: (apprehensive) "Always" is a long time. (they stare at him) Sure, always."

-
 * Its also notable that a drunk and depressed Amy's first instinct was to call Leonard when she needed someone to come and pick her up outside of a liquor store.
 * Took a Level In Jerkass: In early season five he admits to Penny that he only put up with Penny's various quirks to get sex. Also in general he had been putting sex ahead of his friends.
 * This change was largely reverted in mid-season five where he reaffirmed his feelings to Penny and said that it wasn't just missing sex in general but that it was being with her. From there they started hanging out together more often and purposefully backed off on the physical aspect, both seeming happy for it.
 * Translator Buddy
 * The Unfavorite/"Well Done, Son" Guy: With his mom. Doesn't help that Sheldon has a closer relationship with her.
 * Unresolved Sexual Tension: Between him and Penny.

Sheldon Lee Cooper, Ph.D. (Jim Parsons)
"I don't understand why in this group I never get my way."

Leonard's roommate. A child prodigy, he graduated from college at the age of 15 from East Texas and specializes in Theoretical Physics. Supposedly the smartest of the guys, but really the only reason he ends up dominating arguments and debates (both in science and in nerd trivia) is because he is too stubborn to quit and resorts to crazy logic to win. His dedication to science and geekdom is so complete that he has almost no interest in social skills, regular pop culture (current fads, celebrity gossip, etc) or even romance. He thinks he's superior to ... well, to everyone. - "Penny: I know this is none of my business, but I just... I have to ask: what's Sheldon's deal? Is it girls...? Guys...? Sock puppets...?
 * Asexuality: Sheldon is conspicuously uninterested in romance, and is one of those rare TV characters whose asexuality is made more or less explicit in-universe.

Leonard: Honestly, we've been operating under the assumption that he has no deal.

Penny: Come on, everyone has a deal.

Wolowitz: Not Sheldon."

"Sheldon: Yes, my father taught me when I was young. *sigh* It's funny how such a simple action can bring back the smell of cheap bourbon... I would have made such a good elf."
 * Ambiguous Disorder: Sheldon displays symptoms of lots of different disorders depending on Rule of Funny.
 * The Archer: Apparently. While playing some Wii Sports Resort, Leonard comments that Sheldon is really good at the Archery game.

""You want me to share credit?"
 * He also mimes pulling an arrow out of a quiver before making his shot. And wears an arm-guard and modified leather glove.
 * Attention Deficit Ooh Shiny: Lapses into this when he gets fired since he has nothing to focus on.
 * Berserk Button: Sheldon usually doesn't resort to physical violence but question the legitimacy of his work and back up your claims with tangible proofs and all bets are off!
 * WHEATOOOOOOOOOOOOOOOOOOOOOOOON!!!!!
 * Mee-Maw
 * The following exchange:

"Yes."

"GET OUT.""

"Sheldon: *Karate-chops Leonard* She is NOT for you!"
 * Beta Couple: Although his relationship with Amy is a complex one, it is significantly more stable then Leonard/Penny.
 * Break the Haughty: His inflated sense of entitlement and superiority often end up putting him through a thorough, and often well-derserved, Humiliation Conga. Subverted in that he never looses his arrogance, no matter how hard he may have been humiliated.
 * Brutal Honesty: Subverted. With Sheldon, honesty is more about insulting people's intelligence rather than just being straightforward.
 * Butt Monkey: Often on the receiving end of a lot of humiliation and punishment. Not that he doesn't bring it on Himself though.
 * Calling Your Bathroom Breaks: Socially awkward in this department doesn't even begin to cover it.
 * Can Not Tell a Lie
 * Cannot Keep a Secret: He either slips into I'll Never Tell You What I'm Telling You or comes up with needlessly-elaborate lies that fall apart under their own weight.
 * Catch Phrase: "Bazinga".
 * Celibate Hero: As far as being openly contemptious of any kind of sexual desire.
 * Celibate Eccentric Genius
 * Character Development: Sheldon hanging out with Penny and the gang leads him to become more and more human. Three particular Season 5 episodes involve him pushing out his personal boundaries, discovering that his rigid scheduling to regulate his life doesn't need to be so inflexible and his life won't collapse if he does things a little differently now and then. And of course,.
 * Characterization Marches On: Sheldon wasn't quite as socially inept or uptight in earlier episodes and may not even have been established as asexual yet. He was still an arrogant jerk, but not overbearingly so. Take the very first episode for instance: he advises Leonard that discussing bowel movements isn't appropriate when he invites Penny to lunch, he casually refers to Penny being beautiful and immediately recognizes Leonard is attracted to her, and when they visit a sperm bank Leonard makes an off-hand comment that Sheldon is a "semi-pro," the implications in such a context should be obvious.
 * It also becomes a Running Gag as early as the second episode that Sheldon rarely understands sarcasm. In the first episode, nearly all of his jokes are deadpan sarcastic quips at Leonard's expense.
 * As far as his arrogance is concerned, in later episodes it becomes a challenge to get Sheldon to admit that he's wrong regardless of whatever outrageous thing he's done or said. In the second episode, although he still believes that cleaning Penny's apartment without her permission was the right thing to do, he offers a sincere apology to her face after some prodding by Leonard.
 * (Former) Child Prodigy: While he definitely was, attending college at 12 and getting his first of two Ph.Ds at age 16, it's possible he's a deconstruction of the concept. His intelligence vastly alienated him from his family, gave him a big ego, made him highly neurotic and socially inept, and though it may or may not be related to his childhood brilliance he's also something of a man-child.
 * Clingy Jealous Guy: If any guy shows minor interest in Amy Farrah-Fowler.

"Penny: Why do you hang out with him?
 * Cloudcuckoolander
 * Deadpan Snarker: Emphasis on the deadpan.
 * The Friend Nobody Likes

Howard: We like Leonard..."

"Leonard: "Why did you do that?"
 * Genius Ditz: He's a brilliant scientist but is absolutely, painfully clueless in almost every other aspect of life.
 * Green-Eyed Epiphany: Season 5 shows that Sheldon has grown very possessive of Amy, if nothing else. When Leonard states that he and Amy had quite a fun time together at a wedding party and playfully threw in sexual innuendo about this "fun time", Sheldon's reaction? A karate chop to Leonard's neck and then:

Sheldon: "To send a message: She's not for you."

Leonard: "What?"

Sheldon: "Not. For. You.""

""I have never said that you [Howard] are not good at what you do. It's just that what you do [Engineering] is not worth doing.""
 * Hard On Soft Science: Exaggerated with him to the point of absurdity. Not only does he regard the social sciences as "largely hokum", he also speaks disparagingly of other hard sciences, referring to the geology department as "the dirt people" and having a falling out with Leslie Winkle for supporting physics theories he doesn't.
 * Hard On Soft Science: Exaggerated with him to the point of absurdity. Not only does he regard the social sciences as "largely hokum", he also speaks disparagingly of other hard sciences, referring to the geology department as "the dirt people" and having a falling out with Leslie Winkle for supporting physics theories he doesn't.

""He doesn't understand when he is being rude because that part of his brain is getting a wedgie from the rest of his brain.""
 * Hates Being Touched: At least partially due to germophobia.
 * Hates Small Talk: It's not that he hates small talk; it's that his idea of small talk consists of advanced physics theory, comic books and Star Trek canon, and obscure factoids he finds fascinating (even if no one else does). Things such as gossip, sports or personal relationships, he couldn't care less about.
 * He Cleans Up Nicely: When he has to give a speech, Penny takes him out to buy a new outfit. Sheldon emerges from the change room wearing a very nice black suit--cue Jaw Drop form Penny and whistles and hoots from the Laugh Track. Sheldon, being Sheldon, however, finds the outfit absurd.
 * Heroic Sacrifice: Not a lethal one, but during a paintball war his comrades (Leonard, Howard, and Raj) have no enthusiasm due to prior events, and don't really want to fight. Sheldon proceeds to walk outside, into the open, and take several shots to motivate them into fighting, resulting in victory. Complete with slow-motion.
 * Hollywood Nerd
 * Honor Before Reason: Will often avoid taking the easy way out of things, though this usually leaves him worse off than before.
 * Innocently Insensitive: Even when he's trying not to be an Insufferable Genius (usually at the request of one of the other guys), he has a problem of insulting people anyway without realizing it. It's debatable whether or not he realizes how insufferable he really is.
 * Insufferable Genius: He's that page's image for a very good reason.
 * It's All About Me: Delves into this every now and then. But he isn't so selfish to the point of being utterly unlikeable. See Jerk With a Heart of Gold below.
 * Jerkass <---> Jerk With a Heart of Gold: He really is a good guy deep down and shows concern and attention for his friends in his own ways. The problem is his perspective on social interactions are skewed and he doesn't understand when he does something offensive or inappropriate, and he's constantly flaunting what he considers his superior intellect.
 * A perfect example of this, a Season 5 episode ended with Howard asking Sheldon to give him a compliment, such as telling him he's good at what he does. Sheldon is confused and promptly explains he's never said Howard wasn't, of course Howard is skilled in his field, Sheldon just has no respect for said field. Leonard notes it's one of the nicest things he's heard Sheldon ever say.
 * Explained well by Bernadette:

"She's a girl and she's my friend, but there's no touching or unsanitary exchange of saliva."
 * Know-Nothing Know-It-All: Sheldon tends to lapse into this when he veers away from physics and into the life sciences.
 * Sheldon also acts like he knows United States history when he does not. Sheldon tries to convince Leonard that he should be a history professor instead of a physicist by testing whether Leonard knows that slavery in the United States ended in 1863. It didn't.
 * Literal Minded
 * Lovable Nerd:
 * Mad Scientist: Has about as many shades as you can get while still being thoroughly grounded in reality. He alludes to be willing to try electric shocks as negative reinforcement to modify Penny's behavior, mentions he tried (and perhaps succeeded) to build a "death ray" as a child, planned to create a griffon as a child by cross-breeding lions and eagles, and is mentioned to have his computer activities monitored by the government due to his attempts to hack their systems.
 * Lampshaded by Leonard, who notes Sheldon is "one lab accident away from becoming a supervillain."
 * Man Child: Variation. He's completely unaware of this and dismisses as "ridiculous" any claim made in that sense. But many characters, point out at how disturbingly childish his attitude can be at times for a man in his 30's.
 * Meaningful Name: Named for television producer Sheldon Leonard and possibly for physics Nobel Laureate Leon N. Cooper.
 * Momma's Boy
 * Mother Nature, Father Science: A rather blatant example with Amy who is a biologist and him a physicist.
 * Neat Freak
 * Nerd
 * No Sense of Humor: Zigzagged. Sheldon has a sense of humor, but it's so separate from everybody else (except for Amy) that he doesn't get most jokes and most people don't get his.
 * And he always explains his jokes.
 * No Social Skills
 * One of the Kids: So very much. He's finicky, unreasonable, doesn't understand any social conventions, can't stand people fighting, sulks and hides in his room if he doesn't get his way and forces everyone around him to do what he wants whenever he wants.
 * Pride: A lot of the problems he encounters could be avoided if he wasn't so arrogant and proud. A good example is "The Excelsior Acquisition", where he tries to fight a traffic violation on principle when a scene just before he finds out about his summons establishes he has several thousand dollars in uncashed paychecks.
 * Rail Enthusiast
 * Sacrificed Basic Skill for Awesome Training: Sheldon is such a Child Prodigy that he entered college at age 11 and graduated with honours at 14. He has devoted pretty much his entire life to research since then, and this may have contributed to his lack of rudimentary social skills (such as not gloating at a judge) and his overall inability to deal with the mundane world (germophobia for instance).
 * Sarcasm Blind
 * Sesquipedalian Loquaciousness
 * She Is Not My Girlfriend: Amy. On his own words:

-
 * Small Name, Big Ego: Check "Know-Nothing Know-It-All". He believes himself to be multitalented when his only real skill is in Science. He is also very unaware of how much people dislike him and can't understand why They wouldn't want to spend time with Him.
 * Smart People Play Chess: Three-dimensional chess!
 * They also create 3-man chess, complete with new pieces.
 * Southern-Fried Genius
 * Spotlight-Stealing Squad: Leonard was intended to be the main character.
 * Super OCD: Don't sit on his favorite couch cushion, you'll smush it out of shape.
 * TV Genius
 * The Un-Smile: Look at that page image and be prepared to be terrified. Though it should be mentioned...
 * When He Smiles: ...His real smile is actually quite stunning.
 * Whoopi Epiphany Speech: Played with. While such a speech is usually one of great wisdom made by someone who isn't all that educated or book smart, it can't be said that Sheldon is either of those things. But he is very socially inept. So it comes as a surprise at times when Sheldon has rare gems of social wisdom (albeit wrapped in Sesquipedalian Loquaciousness) that give Leonard new insights he couldn't see before.
 * Whoopi Epiphany Speech: Played with. While such a speech is usually one of great wisdom made by someone who isn't all that educated or book smart, it can't be said that Sheldon is either of those things. But he is very socially inept. So it comes as a surprise at times when Sheldon has rare gems of social wisdom (albeit wrapped in Sesquipedalian Loquaciousness) that give Leonard new insights he couldn't see before.

Howard Wolowitz, M.Eng. (Simon Helberg)
"The way I see it, I'm halfway to pity sex."

Of the four male leads, the only one without a doctorate (for which he gets made fun of a lot despite that he has a master's degree from MIT and is an aeronautical engineer). As no group of geeks is complete without a Basement Dweller, he lives at home with his mother despite being in his late 20's at the start of the show. In addition, he is Jewish and practices the faith but does enjoy not eating kosher from time to time. - "Penny: "That was the most beautiful thing I've ever heard, and it came from YOU!""
 * Basement Dweller
 * Casanova Wannabe
 * Character Development: After getting together with Bernadette, he's actually started to become nicer, more honest and less sleazy. He could still be a Jerkass from time to time, but he's still better than before. The few times his sleazy personality shows up (ie. ogling women at a gym) it only serves to remind you of how far he's come. This comes to a head in season 5's "Stag Convergence" where he openly admits to Bernadette he is disgusted with how he was before and that he changed because of her.

-
 * Cunning Linguist: Or so he thinks. In reality, he only knows enough of each language he claims to speak in order to hit on women unsuccessfully.
 * Deadpan Snarker: Over the course of time, he evolved into the second-biggest one among the group, after Penny. From the second biggest snark-catcher, no less.
 * The Engineer
 * Friend to All Children: Sort of. At least in contrast to his fiance.
 * Handsome Lech: How he sees himself, although really he's Casanova Wannabe.
 * Hidden Depths: In a Season 5 episode he admits he's always wanted children, showing behind the sleazy flirting he's always wanted to settle down and raise a family.
 * Hollywood Nerd
 * Homoerotic Subtext: With Raj.
 * Informed Judaism
 * Jewish and Nerdy
 * Lovable Sex Maniac
 * Man Child: When around his mother.
 * Nice Jewish Boy: Inverted. Nice Guy is probably the last thing you'd use to describe him.
 * Sensitive Guy and Manly Man: Manly Man to Raj's Sensitive Guy.
 * Of course, his interpretation of manly is more just being unabashedly sleazy.
 * Small Name, Big Ego: With regards to his skills with women.
 * That Man Is Dead: Regarding his sleazy persona.
 * They Do: With Bernadette.
 * Two Decades Behind: His outfits.

Rajesh "Raj" Koothrappali, Ph.D. (Kunal Nayyar)
"Excuse me! I have selective mutism, a recognized medical disorder. You're just a douche."

The Token Minority, Raj is from New Delhi working in America on a visa as an astrophysicist. He is so shy around women that he is incapable of talking in their presense (even if not speaking to them, he can't talk if they are a part of the social group), eventually identified as Selective Mutism. The most consistent method of overcoming this is through alcohol, but he has tried several anti-anxiety medications with varying results. - "Raj (to Howard): Last night I had a dream, we got so rich from the app we made, you and I bought matching side by side mansions. But, there was a secret tunnel connecting your front yard to my back yard. What do you think it means?
 * Ambiguously Gay

Howard: It means next time we play squash I'm showering at home."

-
 * The fact that he repeatedly claims that he is actually not gay makes Raj even more ambiguous.
 * Adorkable: Many women find him "a cutie-pie" and if any of the guys is to succeed in one of their from-time-to-time escapade for wooing girls, it's usually Raj.
 * Bitch in Sheep's Clothing: Howard points out that it's his inability to talk around women that keeps his less pleasant traits hidden in some contexts.
 * Bollywood Nerd
 * Camp Straight: Dance number aside, he is definitely not gay.
 * Cannot Talk to Women: When sober.
 * Cultural Rebel: Raj hates India and everything to do with it, including and especially Indian food. He dreads talking to his parents for this reason, knowing they're going to try to guilt him into returning there.
 * The Cutie
 * Everything Is Racist: To him...
 * Foreign People Are Sexy: ...but he still tries to milk this for all it's worth.
 * Funny Foreigner
 * Handsome Lech: When drunk.
 * Heterosexual Life Partners: With Howard
 * Hidden Depths: He has some talent in party-planning.
 * Hollywood Nerd
 * Homoerotic Subtext: With Howard they actually kiss once, not intentionally though. He is also enticed by Leonard's demostration of confidence.
 * In Vino Veritas: Can only talk to girls if drunk or medicated.
 * Lovable Nerd
 * Non-Idle Rich: Raj's family apparently is very wealthy.
 * Only Sane Man
 * Queer People Are Funny: Most of the gay jokes of the show comes from Raj.
 * The Quiet One: His inability to talk to girls while sober aside, he is decidedly the one of the foursome who talks less - in many scenes, his participation consists basically of throwing a snarky comment here and there.
 * Real Men Wear Pink: Loves disco dancing, Twilight books and Sandra Bullock films.
 * Sensitive Guy and Manly Man: Sensitive Guy to Howard's Manly Man.
 * Interestingly, his sensitivity only became apparent after Leonard's mother suggested he was gay.
 * Shrinking Violet: Around women.
 * Spoiled Sweet: Raj is from a very wealthy family, but instead of being your typical assholish Rich Bastard, he's a nice and considerate guy, if kinda quirky.
 * Took a Level In Jerkass: Has started going down this direction. At the beginning of the series, he was actually one of the nicest ones in the group. But as of season 4,
 * Although late in Series 4, it appears he's trying out new anxiety medications (one has the memorable side-effect of causing him to walk around nude). The following episode has Raj behave repeatedly as a Jerkass, tormenting Sheldon's germophobia, snarking at Leonard's relationship with his sister and repeatedly uses Double-Entendres during their card games. When you realise he acts just as arrogant and snarky when he's drunk, this could be a side effect of new medication.
 * Howard did say that he was as obnoxious as when he is unable to talk to women, it's just that his inability to talk to women sort of limits how visible his jerkiness is.
 * The Voiceless: Whenever a woman is around.

Penny (Kaley Cuoco)
"You know where I was all afternoon? Auditioning with 50 other blondes for an anti-depressant commercial... (almost in tears) They said I was too perky..."

Nebraska-born neighbor of Leonard and Sheldon, moved there in the pilot. She aspires to be an actress, but to pay the bills she works as a waitress at the Cheesecake Factory. Initially friendly but distant to the guys, she grew to become One of the Boys. She has an average intelligence which is overshadowed by being around these super-geniuses, but displays common sense and social awareness that the others almost completely lack. Her relationship with both Leonard and Sheldon opened her up to the concept of higher thinking and she has found some difficulty going back to keeping "regular" people as company. -
 * All Girls Want Bad Boys: Has a bad case of this.
 * Arguably more of Horrible Judge of Character
 * Better As Friends: She feels that things are easier with Leonard as friends rather than as a couple, though their attraction to each other hasn't ever wavered.
 * Book Dumb: Even by normal standards, she's pretty clueless when it comes to anything academic.
 * Cat Fight: In one instance.
 * Character Development: The first season she was friendly with the group but didn't really hang out with them much. By the second season she started to consider them to be some of her best friends and was even retaining some of the scientific principles the others would explain to her. After getting together with Leonard and later breaking up, she found that she couldn't go back to dating dumb guys again.
 * Cool Big Sis: Once she fully integrated into the group.
 * Also appears to have become this to Amy and Bernadette.
 * Deadpan Snarker: Has increasingly evolved into one as the show continues.
 * Mainly towards Sheldon, more than likely a result of of his verbal abuse.
 * Dumb Blonde: In the early episodes she seemed to be a ditz, but as the series progressed she showed average-level intelligence and a knack for pop culture. She's still dumb if you compare her to the boys and the resident Brainy Brunettes Amy and Leslie, but given all of those characters are explicitly stated to range from above average to abnormal intelligence, a straight-up comparison seems unfair.
 * In fact, as time goes on she seems to be of above-average intelligence. She is uneducated (though this appears largely by disinterest, not by a lack of resources) especially compared with the other guys, but she is easily able to keep up with them in conversation, especially after she's been around them for awhile. She has picked up a lot of their cultural references and has also come to understand some of the science, too, though she obviously isn't as "left-brained" as the scientists are. But it's interesting to realize that she has moved from being more party-oriented and having a lot of loose friendships to becoming a member of a very close group of friends (including Bernadette and Amy), out of whom she is not only the single member without any college education, but also the single member who does not work in science.
 * The Face: Besides being the only female lead, Penny is the only one of the five who is not a socially incompetent nerd.
 * The Chick: Again, she's the only female lead.
 * The Big Guy: She's more capable of handling herself on a physical level then the guys are.
 * Gamer Chick: Has shades of this with her Age of Conan addiction and swift mastery of Halo multiplayer. Not to mention her defeat of Leonard at chess (the same day she learned the rules!) in season 5.
 * Good Bad Girl
 * Hair of Gold
 * Hidden Depths
 * Instant Expert: If she is genuinely interested in playing a game, she tends to be almost a savant at it. She was better than Sheldon her first time playing Halo and beat Leonard at Chess while he was teaching her how to play.
 * Love Interest: For Leonard, thus providing much of the show's plot impetus.
 * Masculine Girl, Feminine Boy: Masculine Girl to Leonard's Feminine Boy.
 * Ms. Fanservice
 * Nerd Nanny
 * Odd Friendship: Towards everyone.
 * Penny and Sheldon, who initially had mutual loathing for each other, eventually evolved into them becoming Vitriolic Best Buds by the end of Season 3. By Season 4, when Leonard gets a new girlfriend and Penny decides to keep her distance, she comments how she's missed being around to hear Sheldon's "jibber jabber".
 * Similarly, she admits she considers even Howard a friend of hers by the end of Season 4 (Even if she did once break his nose for him trying to stick his tongue down her throat)
 * Official Couple: With Leonard
 * Only One Name: Her last name is not revealed.
 * Bill Prady has said that her last name will be revealed eventually.
 * Parental Substitute: She is often one for Sheldon.
 * Team Mom: Sometimes she plays the part for the other boys as well.
 * Unresolved Sexual Tension: Between her an Leonard. The main thrust of the show, nudge nudge, the "bang" in the Big Bang.
 * Too Dumb to Live: Pops occasionally with her no way knowing to check her engine and forgetting that Sheldon has a special spot on the couch
 * Waiting for A Break
 * Women Are Wiser
 * Valley Girl: Played this way near the beginning when set up as Leonard's love interest. Since then, her rather sordid Nebraska upbringing moved into a Cool Big Sis mindset.
 * Women Are Wiser
 * Valley Girl: Played this way near the beginning when set up as Leonard's love interest. Since then, her rather sordid Nebraska upbringing moved into a Cool Big Sis mindset.

Amy Farrah Fowler, Ph.D. (Mayim Bialik)
"Aw, it's the alcohol and drug peer pressure my mother warned me about, I was beginning to think it was never going to happen. Yes please!"

Sheldon's nerdy Distaff Counterpart, the group found her during a dating site prank they pulled on Sheldon. She grows attached to Penny and becomes both her best friend and Foil. As a result she formed a distaff relationship compared to Sheldon and Leonard. While she mirrored Sheldon in almost every aspect initially, over time she branched out through both her friendship with Penny and feeling a romantic attraction to Sheldon. - -
 * Actor Allusion: Amy is a Neurobiologist which Mayim Bialik actually has a Ph.D. in. There's a bit of a mindscrew as Mayim the actor was mentioned on the show before she came on board, Raj referred to "that girl from Blossom being really smart."
 * Adorkable: When Stuart expressed an interest in Amy his reasons for it was that she didn't look upon him "with ball-shriveling contempt." Basically saying that she was cute and not intimidating.
 * Ambiguous Disorder: Even more so then Sheldon at times, although she is more outgoing.
 * Ambiguously Bisexual: Though her interest in males has developed a bit since her initial appearance, she's very appreciative of Penny and fawns over her more than any other character seen in the show thus far. She's made a few sparse comments of the same type about Bernadette as well. For an example she gave Penny a very large painting of the two of them, and told her that it originally had the two of them nude but she had it changed as she didn't want it to "challenge their heterosexuality".
 * An alternative to this is more of a perpetual Stupid Sexy Flanders, she's straight but openly appreciates the attractiveness of her own gender.
 * One time, Amy mentions Penny has a better chance of getting with her than Leonard does.
 * Broken Bird: Unlike Sheldon who is implied by family members to have always been as he is, there's hints that Amy had a very lonely and troubled childhood that resulted in her current character.
 * Brutal Honesty: Amy is a firm practitioner of this. However, unlike Sheldon, she doesn't mean to insult by using it.
 * Catch Phrase: "Hi, bestie" to Penny.
 * Closer to Earth: While she's Sheldon's intellectual equal, she gloats less (though she's just as blunt), is more aware of social norms, and actually has some desire to be normal. She also doesn't seem to have any geeky interests like Sheldon.
 * Covert Pervert: Though she doesn't actually make any attempt to actually hide it, it's still pretty surprising whenever she not-so-subtly talks about her masturbatory habits.
 * Distaff Counterpart: Though she's slowly evolving into her own uniquely awkward character.
 * One of the major ways she's grown is from shifting her primary focus from being Sheldon's friend who is a girl, to being "besties" with Penny. This is somewhat amusing when you realize that she stopped being Distaff Counterpart to Sheldon, to form a Distaff Relationship of Leonard/Sheldon.
 * Divergent Character Evolution: When she was first introduced she was just a female Sheldon. Since she's become friend with Penny and begun to open up socially she's far more normal, though still eccentric and emotionally repressed, and has less patience for Sheldon's quirks than before. Compare an early Season 4 episode where she introduced Sheldon to her mother as her boyfriend so she wouldn't be pressured into actually getting one, and Season 5 where.
 * Generic Cuteness: Averted. While Amy is by no mean "ugly", she definitely looks unusual in comparison to Penny, Bernadette or even Priya (Raj's sister) or Sheldon's sister. Mayim Bialik brings this up about herself in this interview about "geek girls" with Kari Byron of Myth Busters.
 * Give Geeks a Chance: An extremely Rare Female Example.
 * Harp of Femininity: She is seen owning one in later episodes and often plays it for recreation or when she's sad.
 * I Just Want to Have Friends
 * Intelligence Equals Isolation: Unlike Sheldon, she went unwillingly through this, hence her craving for social interactions in general, especially with other women.
 * Insufferable Genius: Not as much as Sheldon though.
 * Jerk With a Heart of Gold: She genuinely doesn't seem to realize how rude she she can be (especially to Penny), but when she thinks Penny's depressed she rushes to cheer her up.
 * Meganekko
 * Mother Nature, Father Science: She forms a classic scientific duo with Sheldon with her in Biology (nature) and Sheldon in Physics (hard science).
 * No Social Skills: Zigzagged. Amy has no natural social skills, but as a neurobiologist, she is fascinated with societal behavior, and knows about a lot of them. However, it's all book knowledge, and she's both poor at application, and there are rather big holes in her knowledge.
 * Princess Phase: She seems to have one deep within, and Sheldon brought it to the surface when he gets her a tiara as an apology for a fight they had.
 * Punny Name
 * Queer People Are Funny: She's the go-to girl for when the gay jokes turn lesbian
 * Sixth Ranger
 * The Stoic
 * TV Genius

Bernadette Rostenkowski, Ph.D. (Melissa Rauch)
"I took Howard to the beach once. He nearly burst into flames like a vampire!"

Howard's miniature-sized romantic interest. A microbiologist, she is often the voice of reason and by far the gentlest character of the show. In a contrast to the other scientists of the show, she doesn't have much difficulty in navigating a successful social life. Despite being sweet and bubbly, she can and has gotten angry enough to scare the others. She started out as a friend of Penny who also worked at the Cheesecake Factory to pay for her schooling, she later graduated with her doctorate and is working a very lucrative job for a pharmaceutical company. - "Howard's Mom: (regarding a custom made vest) She has a tricky figure, she's short and stacked like me!"
 * Beware the Nice Ones
 * Buxom Is Better: She is fairly well endowed, and this was mentioned in the show.

-
 * Characterization Marches On: One of her defining traits in her introductory episode is that she didn't really get any of the jokes the others would share. Her second episode was similar (In response to Howard seriously proposing to her "Is this one of those jokes I don't understand?"). In her third episode she admitted to laughing just because it made Howard smile, while still not getting them (though she would try to explain some jokes to the others). Since then it's never reappeared.
 * The Chick: More so than Penny.
 * Child-Hater: It stems back to when she was forced to take care of her younger siblings because her mother worked full time. This caused problems for Howard, who always dreamed of becoming a father.
 * Closer to Earth: Compared to pretty much everyone (even Penny).
 * Covert Pervert: Don't let her cuteness fool you.
 * Cute but Cacophonic: Sweet Jesus.
 * Cuteness Proximity
 * Dumb Blonde: Completely subverted. She may talk in a cutesy voice and play The Ingenue around Howard, but she's also a microbiologist with an interest in physics as well (she's every bit Howard's intellectual equal).
 * Fun Size: She needs a stepping stool just to see through her peephole.
 * Hair of Gold
 * The Ingenue: She's rather oblivious to Howard's double entendres at first.
 * Kawaiiko
 * Magical Girlfriend: Howard seems to see her as one.
 * Meganekko
 * Noodle Incident: She and her fellow microbiologists apparently crossed the Ebola virus with the common cold. Not that they'd ever admit it. "That would be a terrible, terrible thing!"
 * Obfuscating Stupidity: She admits to do this around Howard at times.
 * Put On a Bus: In "The Plimpton Stimulation". Offscreen, no less.
 * The Bus Came Back: She returned in "The Hot Troll Deviation"
 * Raised Catholic: One reason she and Howard bond is because of their shared rebellion against their religious traditions.
 * Sarcasm Blind/Captain Obvious
 * Sickeningly Sweethearts: With Howard.
 * Silk Hiding Steel: Despite her height, her apparent meekness and her mannerly behavior, she's among the rare characters able to make Sheldon shut up and abide. She can even handle Howard's mother, which is NO easy feat.
 * Seemingly-Wholesome Fifties Girl: See Covert Pervert. Part of it is as backlash to her strict Catholic upbringing (see above).
 * Smarter Than You Look: People tend to forget she is a microbiologist due to her Kawaiiko personality.
 * She once said she either wanted to be a microbiologist, physicist, or an ice dancer.
 * Team Mom: She can even handle Sheldon.
 * They Do: With Howard.

Stuart Bloom (Kevin Sussman)
""Okay, if you are going to question the importance of an actor's signature on a plastic helmet from a movie based on a comic book then our lives have no meaning!""

The owner of the comic book store the group frequents. - -
 * Characterization Marches On: In earlier episodes he was a Cool Loser contrast to the group, but was able to successfully flirt with and ask Penny out. In time he became even more pathetic and helpless, and mentions at one point he lives in the store due to financial problems.
 * Genre Savvy: He knows how to entice the geeks pretty well, taking about how a sword was "limited edition" (only 5,000 of them) which sent Sheldon in a frenzy.
 * Recurring Character: One of the most frequent recurring characters, mentioned in season one but not seen until late season two.
 * Ship Tease: Dates Penny and Amy for one episode each, both of which force Leonard and Sheldon to reconsider their relationship with those girls.

Leslie Winkle (Sara Gilbert)
"You put electrodes in a rat's brain and give him an orgasm button he will press that thing until he starves to death."

Sheldon's enemy at the college, she never passes up a chance to insult him. - -
 * Ascended Extra/Demoted to Extra: Began to become a more prominent character, but faded away again when her character proved uninteresting outside of her rivalry with Sheldon.
 * Berserk Button: She will do anything to show up Sheldon if he's mentioned.
 * Casting Gag: Sara Gilbert and Johnny Galecki were married on Roseanne, Leslie happened to be the first girl of any significance in Leonard's life on the show.
 * Deadpan Snarker
 * Ship Tease: She and Leonard have hooked up twice, though the first time was purely for the sex, and there have been other hints when they're separated.
 * Sitcom Arch Nemesis: With Sheldon.
 * Static Character: Leslie was fun because she was so dry and deadpan, as well as obnoxious to Sheldon. Instead of trying to change her to be capable of growing like the main cast, they made her into a sporadic recurring character.

Mary Cooper (Laurie Metcalf)
"(to Sheldon about his lack of childhood friends) "Honey, they knew plenty well why they hated you.""

Sheldon's mother, she's a religious fanatic who, despite their differences, is very close to Sheldon emotionally. -

-
 * Brutal Honesty: Not the same as Sheldon but very blunt all in all.
 * Casting Gag: Like Sara Gilbert and Johhny Galecki, another Roseanne alum.
 * Cool Old Lady
 * Innocently Insensitive: For one example, she mentions her priest could try to perform an exorcism on Raj to rid him of "foreign devils" that inhibit his ability to talk to women.
 * Foil: To Beverly Hofstadter. She is everything Leonard's mother is not.
 * The Fundamentalist.
 * Nevertheless she's still a Cool Mom.
 * Hollywood Old: Defied. Her age is never mentioned but she looks like she gracefully aged into her mid 50's.
 * Purity Sue: Has a few traits of this, largely in that everyone loves her. She has a bit of "righteous condemnation" attitude but admitted to Penny that at her age any guy could have her with a car and a bottle of strawberry wine.
 * To be fair, she is one of the few people who can actually control Sheldon, therefore leading to everyone loving her.
 * You Are a Credit To Your Race: She makes blindly racist jokes but are not really meant in an offensive manner, she's just an old-school conservative.

Beverly Hofstadter (Christine Baranski)
"Excuse me Leonard, I am the one getting a divorce, Mitsy is the one who is dead, why are you the one making a fuss?"

Leonard's mother, she's emotionally distant and entirely cold to him, but finds a kinship in Sheldon. - -
 * Abusive Parents: Made worse by the fact that whatever damage was done was seemingly unintentional.
 * All Psychology Is Freudian: Played with. Despite being a trained psychiatrist and acknowledging that Freud's theories are outdated, she still invokes this to manipulate Penny to the point of tears.
 * Calling Your Bathroom Breaks: Without even a hint of shame, at that.
 * Covert Pervert: Alcohol brings it out.
 * Distaff Counterpart: To Sheldon, before Amy was introduced.
 * Emotionless Woman
 * Foil: To Mary Cooper who she is the exact opposite of.
 * Ice Queen: Plays the archetype straight throughout the series' run. She never shows warmth or nurturance of any sort towards anyone, coldly deconstructs anyone she talks to and remains mostly immune to the Defrosting Ice Queen effect. However, she does loosen up a bit around Sheldon, simply because they have so much in common.
 * Hard On Soft Science: According to her, she and her husband (an anthropologist) wrote a paper on the same subject (Leonard's parenting). Hers was "the only one worth reading, of course".
 * Lack of Empathy: For a good example, take note of the quote.
 * Mind Rape: The resident mistress of this.
 * Running Gag: She likes to give people cat scans.

Barry Kripke (John Ross Bowie)
""We're all pathetic and cweepy and can't get girls. That's why we battle wobots.""

Another rival at the university. - -
 * Always Someone Better: If he's featured in an episode, by the time it ends he'll have faced at least one of the guys and come out the winner. Most prominent when they face him in a Battlebots fight.
 * Elmuh Fudd Syndwome: And just look at his name.
 * The Gambling Addict: Implied, given he willingly went to Sheldon's party only because there's going to be a raffle.
 * The Rival: To Sheldon, and to a lesser degree the other three guys (though they seem to get along with him okay).
 * How well the others get along with him seems to change from episode to episode. A couple examples: Raj once called Kripke a "ginormous knob;" just before that, Kripke sarcastically congratulated Leonard on an experiment of his that went nowhere. Yet in another episode, when Kripke pulled his helium prank during Sheldon's NPR interview, he held up the radio for Raj, Leonard and Howard to listen to, to their riotous laughter.

Zack Johnson (Brian Smith)
""I was watching the Discovery Channel and they said if you cut a Starfish in half it will just come back to life.""

A brief boyfriend of Penny's who becomes friends with the guys. - -
 * Brainless Beauty
 * Dumb Is Good: Incredibly dense, but is very open and friendly with the guys.
 * Hidden Depths: While he is hopelessly unable to grasp the actual science, he still shows an interest in what the guys are doing and apparently watches the Discovery Channel from time to time. He is also apparently very knowledgeable about the designing and creation of restaurant menus.
 * Nice Guy: Got upset when he realized the others were mocking him, but quickly forgave them when offered some Milk Duds.
 * Not So Different: Raj bonds with him after realising that Zack is a comic book aficianado.
 * Sarcasm Blind: To the point that Sheldon seems like an expert.

Wil Wheaton (Wil Wheaton)
""Don't worry, it [being Sheldon's mortal enemy] doesn't take up too much of your time.""

A local celebrity and perpetual rival to Sheldon. -
 * Adam Westing: Takes it to a new art form.
 * Arch Enemy: With Sheldon.
 * The Atoner: Shows signs of this. He invited Sheldon and his friends to a party - and when Sheldon actually shows up, Wheaton gave Sheldon a signed action figure to make up for not showing up at the Star Trek convention Sheldon went to as a child., but at least Wheaton is off Sheldon's Arch Enemy list.
 * Evil Gloating: Gloats that being Sheldon's archnemesis means he lives in Sheldon's head rent free.
 * Jerkass/Jerk With a Heart of Jerk
 * Manipulative Bastard
 * Nice Character, Mean Actor: In the show's universe, Wheaton is a selfish scheming mastermind Sitcom Arch Nemesis who orchestrated the first break-up between Penny and Leonard just to beat Sheldon's team at bowling - a far cry from his character on Star Trek (which is how Sheldon initially knew of him).
 * Mean Character, Nice Actor: Which in turn results in this, since in real life Wheaton is known to be a nice guy.