Esk or ESK may refer to:
- River Esk (disambiguation) - several rivers
- Esk, Queensland, town in Australia
- Shire of Esk, local government area in Queensland
- HMS Esk - several ships
- Elbe-Seitenkanal, canal in Germany
- The girl wizard who is the main character of Terry Pratchett's novel Equal Rites, whose full name is Eskarina Smith.
- Economics of scientific knowledge (ESK)