[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/thebigbangtheory_7.png]]
[[caption-width-right:350:Yes, this is a poster for a show named after the event that created the universe. [[note]]Clockwise from bottom right: [[CuteButCacophonic Bernadette]], [[CasanovaWannabe Howard]], [[FunnyForeigner Raj]], [[BrainyBrunette Amy]], [[LovableNerd Leonard]] and [[GirlNextDoor Penny]]. In the middle just below the logo: [[InsufferableGenius Sheldon]].[[/note]]]]

->''Our whole universe was in a hot, dense state\\
Then nearly fourteen billion years ago, expansion started, wait--\\
The earth began to cool, the autotrophs began to drool\\
Neanderthals developed tools, we built a wall\\
(We built the pyramids!)\\
Math, science, history, unraveling the mystery\\
That all started with the Big Bang (Bang!)''
-->-- '''"Big Bang Theory Theme"''', Music/BarenakedLadies

''The Big Bang Theory'' is a Creator/{{CBS}} {{sitcom}} co-created by Creator/ChuckLorre and featuring four [[TVGenius genius-level]] friends (with careers ranging from theoretical physics to engineering) and [[GirlNextDoor a pretty girl]] who shakes up their dependence on UsefulNotes/TheScientificMethod and geeky lifestyle.

The main characters are two OddCouple roommates, Dr. Leonard Hofstadter (played by Creator/JohnnyGalecki) and Dr. Sheldon Cooper (played by Creator/JimParsons). Leonard is a mild-mannered nerd who, although awkward, is still socially capable. Sheldon is an [[InsufferableGenius egomaniacal supergenius]] who displays signs of USefulNotes/{{OCD}}, [[DistractedByTheShiny ADHD]] and many other mental disorders.

An aspiring actress named Penny (played by Creator/KaleyCuoco) moves in next door, and Leonard almost instantly develops a crush on her, with the [[UnresolvedSexualTension unresolved feelings between them]] creating a good sum of [[RuleOfDrama drama]] and [[StoryArc overarching plot]] over the show's course. Penny is actually a perfectly normal person with an average intelligence level, but compared to Leonard and [[SitcomArchNemesis Sheldon]], she comes across as a DumbBlonde. On the other hand, she is very friendly and outgoing with a vibrant social life and a multitude of interests, [[{{Foil}} contrasting the shy, reclusive personalities of the guys]].

Rounding out the cast are two other genius geeks who are always visiting Sheldon and Leonard: Howard Wolowitz (played by Creator/SimonHelberg), a [[CasanovaWannabe wild but unsuccessful womanizer]] who never stops hitting on Penny; and [[BollywoodNerd Dr. Rajesh "Raj" Koothrappali]] (played by Creator/KunalNayyar), who suffers from [[ShrinkingViolet crippling mutism]] whenever women are around (unless he's drunk).

The third season added two new female characters in semi-regular roles, who would eventually be promoted to the main cast: Dr. Bernadette Rostenkowski (played by Creator/MelissaRauch) a sweet-hearted microbiologist who is introduced as Penny's friend and co-worker at The Cheesecake Factory, and soon formed a relationship with Howard; and Dr. Amy Farrah Fowler (played by Creator/MayimBialik) a DistaffCounterpart to Sheldon who gradually became best friends with Penny and [[DivergentCharacterEvolution eased out of her neurotic shell]]. Bernadette and Amy ended up forming a PowerTrio with Penny that contrasts the four guys and gave the show a new female perspective.

The show's humor can be divided into several categories: [[GeniusBonus obscure references]] to physics or {{geek}} culture, every [[StereotypicalNerd nerd stereotype]] the writers can think of, and the culture clash between Penny and the guys. Any given episode shuffles between romantic comedy/relationship drama, indulging in an established geeky pursuit, and the work lives of the characters at [[http://en.wikipedia.org/wiki/Caltech Caltech]]. Also, for the most part, the references to science and nerd culture are ''[[ShownTheirWork accurate]]'', or at least close enough that somewhere between the writing and the acting, someone knows what they're talking about. The writers consulted Dr. David Salzberg of UCLA for advice on scripts and dialogue, and he personally mapped out [[TheBigBoard the white board equations]].

The show ran from 2007 to 2019, airing its GrandFinale on May 16, 2019, with a total of 279 episodes over twelve seasons, making it [[LongRunner the longest-running multi-camera sitcom in television history.]] In 2017, CBS premiered ''Series/YoungSheldon'', a SpinOff featuring the younger Sheldon dealing with living in Texas as a ChildProdigy, narrated by Creator/JimParsons.

A transcript of episodes can be [[http://bigbangtrans.wordpress.com found here.]]
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!!The Tropes Page Dispersion:
[[index]]
* TheBigBangTheory/TropesAToE
* TheBigBangTheory/TropesFToJ
* TheBigBangTheory/TropesKToO
* TheBigBangTheory/TropesPToS
* TheBigBangTheory/TropesTToZ
!!''[-*knock knock knock*-]'' Tropes? ''[-*knock knock knock*-]'' Tropes? ''[-*knock knock knock*-]'' Tropes?
* TheBigBangTheory/SeasonOne
* TheBigBangTheory/SeasonTwo
* TheBigBangTheory/SeasonThree
* TheBigBangTheory/SeasonFour
* TheBigBangTheory/SeasonFive
* TheBigBangTheory/SeasonSix
* TheBigBangTheory/SeasonSeven
* TheBigBangTheory/SeasonEight
* TheBigBangTheory/SeasonNine
* TheBigBangTheory/SeasonTen
* TheBigBangTheory/SeasonEleven
* TheBigBangTheory/SeasonTwelve
[[/index]]
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->'''Sheldon:''' You're not done with her, are you?\\
'''Leonard:''' Our babies will be smart AND beautiful.\\
'''Sheldon:''' Not to mention imaginary.