Whatchamacallit, a shortened version of "what you might call it," may refer to:
- Whatchamacallit, a placeholder name used for something whose name is unknown
- Whatchamacallit (candy), a candy bar made by The Hershey Company
- "Whatchamacallit", a song from the Pussycat Dolls's album Doll Domination
- Whatchamacallit (album), an album by Brick Layer Cake