With a surname or pseudonym starting with O.
Thornton Oakley (1881–1953)
Georg Oddner (1923–2007)
Frans Wilhelm Odelmark (1849–1937)
Gunnar Odin (1926–1972)
Tom of Finland (1920–1991)
Urho Oinila (1916–1995)
Mikko Oinonen (1883–1956)
Onni Oja (1909–2004)
Feliks Ojanen (1898–1970)
Heli Ojanperä (1921–1994)
Angela Oker-Blom (born 1947)
Aimo Okkolin (1917–1982)
Leif Olausson (1944–2017)
Helle Olin (1906–1944)
Gunvor Olin-Grönqvist (1925–2005)
Vilmalotta Olivia Schafhauser (born 1972)
Edvin Ollers (1888–1959)
Lyyli Ollila (1888–1958)
Yrjö Ollila (1887–1932)
Maiju Ollilainen (1899–1987)
Sager-Nelson Olof (1868–1896)
Pierre Olofsson (1921–1996)
Gudmar Olovson (1936–2017)
Axel Olson (1899–1986)
Bengt Olson (born 1930)
Eric H. Olson (1907–1995)
Erik Olson (1901–1986)
Hilda Olson (1832–1916)
Lars Olson (1931–2020)
Ove Olson (1903–1975)
Eva Olsoni (1908–1994)
Nils Jakob Olsson Blommér (1816–1853)
Arne Olsson (1918–2004)
Axel Olsson (1919–2001)
Emil Olsson (1890–1964)
Henrik Olsson (born 1969)
Karin Olsson (1928–2006)
Sven-Olow Olsson (1924–1971)
Sören Olsson (1914–2002)
Wilgot Olsson (1906–1990)
Wilgot Olsson (1890–1979)
Nils Olzon (1891–1953)
Gunni Omann
Ulf Onsberg (1932–2020)
Johnny Oppenheimer (1923–2005)
Leona Oppenheimer (born 1959)
Johanna Oras (born 1970)
Werner Orjala (1898–1975)
Sir William Orpen (1878–1931)
Vieno Orre (1920–1984)
Erik Ortvad (1917–2008)
Bengt Orup (1916–1996)
Heikki Orvola (born 1943)
Jon Oscar Esti (1887–1955)
Anna-Maria Osipow (born 1935)
Paul Osipow (born 1939)
Olga Osol (1905–1994)
Johan Ossian-Andersson (1889–1975)
Erik Osslund (1913–1982)
Helmer Osslund (1866–1938)
Hans Osswald (1919–1983)
Elvine Osterman (1908–1997)
Hugo Otava (1891–1967)
Olof Ottelin (born 1917)
Alvar Outakka (1897–1951)
Sulo Ovaska (1906–1986)