Cotter may refer to:
- Cotter (pin), a pin or wedge used to fix parts rigidly together
- Cotter (farmer), the Scots term for a peasant farmer formerly in the Scottish highlands
- Cotter (surname), an surname (including a list of people with the name)
- Cotter, Arkansas, United States
- Cotter, Iowa, United States
- Cotter River, a river in the Australian Capital Territory
- Cotter (film), a 1973 film by Paul Stanley