List of people by name: A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z
Oa-Ok - Ol-Oo - Op-Oz
- Olaf I of the Isle of Man, (1137-1153), king
- Olaf II of the Isle of Man, (1229-1237), king
- Olaj, Joze, poet
- Olajuwon, Hakeem, (born 1963)
- Oland, Warner, (1880-1938), actor
- Olaskoaga, Andoni Goikoetxea, athlete
- Olav I of Norway, (969-1000), Norwegian monarch
- Olav II of Norway, (995-1030), Norwegian monarch
- Olav III of Norway, Norwegian monarch
- Olav IV of Norway, (1370-1387), Norwegian monarch
- Olav V of Norway, (1903-1991), Norwegian monarch
- Olbers, Heinrich Wilhelm, (1758-1840), astronomer
- Olcott, Sidney, (1873-1949), directed (1907) Ben-Hur
- Oldebarneveldt, Johan van, statesman
- Oldenbourg, Claes, (born 1929), artist
- Oldenburg, Claes, (born 1929), sculptor
- Oldfield, Barney, (1878-1946), automobile pioneer
- Oldfield, Mike, (born 1953), British composer, musician
- Oldham, John, (1592-1636) Massachusetts pioneer killed by Indians
- Oldman, Gary, (born 1958), US actor
- Oldrich, (1012-1033), Bohemian aristocrat
- Olds, Ransom E, (born 1864), automobile pioneer
- Olds, Sharon, poet
- O'Leary, Jane, member of Aosdána
- Olga of Russia, Grand Duchess, (1882-1960)
- Oliban, Anton, (1824-1860), poet
- Oliphant, Carolina, 18th century composer and songwriter
- Oliphant, Dave, poet
- Oliphant, Pat, (born 1935), political cartoonist
- Oliva, Tony, baseball player
- Olivares, Adrian, (born 1978), singer, first non Puerto Rican Menudo
- Olivares, Ruben, (born 1947), world champion boxer
- Oliveira, Manoel de, (born 1908), (director)
- Oliveira, Sergio Roberto de, composer
- Oliver, Donald H, Canadian senator
- Oliver, Jamie, (born 1975), chef (the "Naked Chef")
- Oliver, Joe King, (1885-1938), musician
- Oliver, John, 1918-03-06 to 1927-08-17
- Oliver, Mary, poet
- Olivi, Peter, (1248-1298), scholastic philosopher
- Olivier, J.H. Ferdinand, (died 1841), German painter
- Olivier, Laurence, (1907-1989), British actor
- Ollenhauer, Erich, (1901-1963), politician
- Oller, Narcis, (1846-1930), author of La febre d'or
- Olmedo, Alberto, (1933-1988), Argentine comedian
- Olmstead, Frederick Law, landscape architect
- Olmstead, Kevin, Who Wants to be a Millionaire winner
- Olmsted, Frederick Law, (1822-1900), architect
- Olof von Dalin, Swedish writer
- Olrik, Axel, (1864-1917)
- Olschanezky, Sonia, (1923-1944), SOE agent, WW II heroine
- Olsen Twins, The, US actresses
- Olsen, Fred, (1857-1933), Norwegian shipping magnate
- Olsen, Kenneth, magnetic core memory - Digital Equipment Corporation
- Olsen, Merlin, (born 1940), American football star, actor
- Olsen, Susan, (born 1961), actress
- Olson, Barbara K, (died 2001), US political figure
- Olson, Bobo, world champion boxer
- Olson, Charles, (Black Mountain School founder)
- Olson, Clifford, convicted serial child killer
- Olson, Lute, (born 1934), college basketball coach
- Olsson, Albert, Swedish writer
- Olsson, Hjort Anders, musician
- Olybrius, (died 472), Roman Emperor
- Olympians, patriarch of Constantinople
- Omaira, George, Maronite Patriarch
- O'Malley, Desmond, founder and first leader of the Progressive Democrats
- O'Malley, Grace, (1530?-1603?), Granuaile,Gráinne Mhaol, pirate queen
- O'Malley, Tony, Saoi of Aosdána
- Omar, Mohammed, (born 1959)
- O'Mara, Peter, musician
- Onassis, Christina, (1950-1988), Greek heir to Onassis fortune
- Onassis, Aristotle, (1906-1975), Greek shipping magnate
- Ondaatje, Michael, (born 1943), author
- O'Neal, Ryan, (born 1941), US television personality
- O'Neal, Shaquille, (born 1972), American basketball player
- O'Neal, Terry A, poet
- O'Neil, Dennis, comic creator
- O'Neil, Ed, comedian
- O'Neill, Eugene, (1888-1953), British dramatist
- O'Neill, Jonjo, jockey
- O'Neill, Kevin, comic creator
- Onesimus, patriarch of Constantinople
- Onic, France, (1901-1975), poet
- Onishi, Takijiro, Japanese admiral
- Onizuka, Ellison, (1946-1986), astronaut
- Onnes, Heike Kamerlingh, (1853-1926), physicist
- Onnis, Vincenzo Brusco
- Ono Yoko, (born 1933), Japanese-born artist
- Onoda, Hiroo, (born 1922), Japanese post-war straggler
- Onoe, Saishu, Japanese poet
- O'Nolan, Brian, (1911-1966), aka Flann O'Brien
- Onopsus of Alexandria, (Coadjutor)
- Onsager, Lars, (1903-1976), physical chemist
- Ontkean, Michael, (born 1946), actor
- Onufrienko, Yuri, astronaut
- Oort, Jan, (1900-1992), astronomer