The Big Bang. The start of the Universe. Scientist have many theories about what it was. But here comes The Reveal... it was the scientists who made it. Or an accident. Maybe even the very protagonists of the story.
Part of the Historical In-Joke, Reality Retcon, or Been There, Shaped History. Compare Beethoven Was an Alien Spy, Phlebotinum Killed the Dinosaurs. Tends to involve a Stable Time Loop. Subtrope of Real Event, Fictional Cause. Can be considered a subtrope of Creation Myth - well, except that this is usually in-universe reality rather than myth.
- Imperiex of the DCU, a hive minded mechanical entity, saw its purpose as being the "hollowing" of the universe, destroying the flawed creation and remaking it in a new Big Bang. Ironically, the flaw it detected in the universe was itself, and a massive cooperative effort managed to throw him into the past where he in fact became the Big Bang in the first place, via a Stable Time Loop, a fact which Imperiex realizes the moment before it dies. Also, it is stated that the reason there is a multiverse is that a scientist decided to view the Big Bang and disrupted it that way.
- Marvel Universe. At the end of the Secret Wars II series the energy of the Beyonder is shunted out of our universe and becomes a Big Bang, thus creating a new universe.
- The Ur-Example seems to be The Accursed Galaxy (1935) by Edmond Hamilton, where it turns out the reason the universe expands is that a race of Energy Beings once faced the disease of life spreading among the planets of the original supergalaxy, and had no choice but to spin it apart. Not quite a bang, but then, the term wasn't coined until over a decade later.
- Isaac Asimov
- The Gods Themselves has the heroes stating at the end that the way they are draining the energy from another universe (which is all a single star) will eventually cause a Big Bang by making the star go supernova. It is unknown whether it happened in our universe, since spontaneous leakages are quite possible.
- The short story "The Instability" ends with two time travelers realizing they didn't travel 27 million years to their own future, but into the primordial chaos of some dimension. And since they are here, they are introducing an instability, meaning... Oh Shi-
- A possible case in A. E. van Vogt's The Weapon Shops of Isher, where a man travels through time, accumulating energy the further he is away from his time. In the end, he is at a time before the planets formed, and is tired of it, so he releases the energy (although it is not stated that outright it is actually the Big Bang that was created that way).
- The Star Diaries has an episode where scientists are trying to send into the past a particle which will become the Big Bang (they are also trying to imbue it with the properties to create a better universe... doesn't really work out).
- In Harry Harrison's Star Smashers of the Galaxy Rangers, it is revealed at the end that the ultimate weapon works by sending an area of space to the past in order to create the Big Bang. Naturally, It Only Works Once.
- In God's Debris, the event known as the Big Bang was actually God killing Himself to experience the only thing He hasn't yet known—His own death. The entire post-BB universe is actually the eponymous debris of God, i.e. matter and probability.
- Soul Music. The first thing ever heard in the universe was "One. Two. One, two, three, four." and then the big bang happened, thanks to "Music with Rocks In", as the main theme of the book is that the music is alive, and wants to be played, no matter the cost to the player. This is in contradiction to earlier books, but Discworld is famously loose with its origin stories.
- Doctor Who:
- In the two-parter, "The Pandorica Opens" and "The Big Bang", the Doctor is forced to restart the entire universe after cracks in reality and timey-wimey paradoxes have made it so that everything never was, using the restoration beam from inside the Pandorica and the energy from the exploding TARDIS.
- In "Terminus", it is revealed that the Big Bang was triggered by a time-travelling space ship that was forced to dump unstable fuel into the void before going back up the timeline. The fuel exploded, triggering the Big Bang.
- Lucifer: Lucifer claims that the "Big Bang" was his parents having sex. His mother seems to support that suggestion.
- In the Doctor Who radio play "Slipback", the Big Bang was caused by the freighter Vipod Mor travelling back in time to the beginning of the Universe and self-destructing.
- 8-Bit Theater: Sarda the Sage went back to the beginning of the universe to create it in his image. However, he carelessly sent White Mage slightly further back, and she accidentally creates the universe as-is first.
- Family Guy
- "The Griffin Family History". When Peter starts telling the history of his family, he starts at the beginning of the universe, which was the result of one of God's farts that he set on fire.
- In "The Big Pang Theory", it turns out the entire universe came into existence because of an accident involving Stewie's time machine.
- In Green Lantern: The Animated Series, to an extent. The Big Bang is completely natural, but Aya tries to mess with it to create a universe she considers better.