Harmaja is an island and a lighthouse outside Helsinki, Finland.
Harmaja may also refer to:
Harmaja (band), Finnish acoustic rock group Harmaja (album), a self-titled album by the Finnish acoustic rock group Harmaja Leo Harmaja (1880–1949), Finnish economist and Director General of the National Archives Service of Finland Saima Harmaja (1913–1937), Finnish poet and writer Tapani Harmaja (1917–1940), Finnish World War II pilot and writer Harri Harmaja (1944–), Finnish biologist and mycologist at the University of Helsinki.