Big Bang Theory most commonly refers to:

• The Big Bang, a cosmological model of the universe
• The Big Bang Theory, an American TV sitcom

It may also refer to:

• "The History of Everything", AKA the theme from The Big Bang Theory, a song by 2007 Barenaked Ladies
• Big Bang Theory (Billy Bang album) (2000)
• Big Bang Theory (Styx album) (2005)
• Big Bang Theory (Harem Scarem album) (1998)

• "Big Bang Theory", Casualty series 20, episode 11 (2005)
• "Big Bang Theory", Hero High episode 23 (1982)
• "Big Bang Theory", NYPD Blue season 6, episode 11 (1999)
• "The Big Bang Theory", Family Guy season 9, episode 16 (2011)
• "The Big Bang Theory", Good Grief episode 12 (1991)
• "The Big Bang Theory", My Wife and Kids season 3, episode 24 (2003)
• "The Big Bang Theory", The Little Couple season 1, episode 12 (2009)
• "The Big Bang Theory", Tyler Perry's House of Payne season 2, episode 52 (2008)

• Big Bang (disambiguation)