Brainiac may refer to:

  • In DC Comics:
    • Brainiac (comics), a fictional supervillain in DC Comics, and an enemy of Superman
      • Brainiac (story arc), 2008 storyline in Action Comics
      • Brainiac (Smallville), version of the villain in the TV series Smallville
    • Brainiac 5, a member of the Legion of Super-Heroes
  • Brainiac (band), an American indie rock band
  • Brainiac: Science Abuse, a British television programme
    • Brainiac: History Abuse, a spin-off of the above
  • The Brainiac, a 1962 Mexican horror film directed by Chano Urueta
  • "Brainiac" (Dark Angel), an episode of the television series Dark Angel
  • Function BRAINIAC, an energy drink
  • Brainiac: Adventures in the Curious, Competitive, Compulsive World of Trivia Buffs, a book written by Ken Jennings
  • brainiac techniques for improving computer performance