Grennan
Grennan is an Irish surname. It may be of Norman origin, from the French name Grenan. Notable people with the surname include:
- Eamon Grennan (born 1941), Irish poet
 - James Grennan, Irish Gaelic footballer who played for Offaly
 - Justin Grennan (born 1978), American singer
 - Keith Grennan (born 1984), American football player
 - Mike Grennan (1950–2009), American curler
 - Seán Grennan, Irish dual player of Gaelic football and hurling who played for Offaly
 - Tom Grennan (born 1995), English singer and songwriter
 - Winston Grennan (1944–2000), Jamaican drummer
 - Jacqueline Grennan Wexler (1926–2012), American academic administrator
 
See also
- Greenan (surname)
 - Julia Grenan (1884–1972), Irish nationalist and socialist in the Easter Rising
 - Grennan (disambiguation)