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 Camp Dennen, found on the shores of Hedges Pond (Plymouth, Massachusetts)
See also Deneen Dineen Dinneen Dannen