Gregan is a surname. Notable people with the surname include:
Brian Gregan (born 1989), Irish sprinter Eugene Gregan (born 1937), American painter George Gregan (born 1973), Australian rugby union player John Edgar Gregan (1813–1855), Scottish architect Miroslav Gregáň (1996), Slovak footballer Sean Gregan (born 1974), English footballer
See also Gregan McMahon (1874–1941), Australian actor and theatrical producer Grogan