Dennen is a surname. Notable people with the surname include:
- Brett Dennen (born 1979), American singer-songwriter
- Barry Dennen (1938–2017), American actor, singer, writer
- Alfie Dennen, British technologist
- George E. Dennen (1884–1966), American reporter and politician
- Lyle Dennen, British Anglican priest
Other
edit- Camp Dennen, found on the shores of Hedges Pond (Plymouth, Massachusetts)