A clapper may refer to one of the following:
- Part of a bell
- Clapper bridge
- A sound-activated gadget called The Clapper
- A character from the video game Donkey Kong Country 2: Diddy's Kong Quest
- Clapperboard used in film production to aid synchronizing audio and video, and to identify different shots
- Clapper (musical instrument) ancient musical instrument that is struck against each other to make noise
- James R. Clapper, the current Director of National Intelligence of the United States of America