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 (comics), a fictional supervillain in DC Comics, and an enemy of Superman
- 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