Free Biography Index - O
- O. Henry
- Octave Crémazie
- Octavia E. Butler
- Octavio Paz
- Oda Nobunaga
- Odilon Redon
- Odoacer
- Ogden Nash
- Okomfo Anokye
- Olaf II
- Olaf Tryggvason
- Olaudah Equiano
- Ole Edvart Rölvaag
- Olive Schreiner
- Oliver Cromwell
- Oliver Ellsworth
- Oliver Evans
- Oliver Goldsmith
- Oliver Hazard Perry
- Oliver Hazard Perry Throck Morton
- Oliver Hudson Kelley
- Oliver Otis Howard
- Oliver Reginald Tambo
- Oliver Stone
- Oliver Wendell Holmes
- Oliver Wendell Holmes Jr
- Olivier Messiaen
- Olympia Snowe
- Omar Khayyam
- Omar Nelson Bradley
- Omar Torrijos
- Omar al-Mukhtar
- Omar ibn al-Khattab
- Ong Teng Cheong
- Orcagna
- Orestes Augustus Brownson
- Origen
- Osama bin Laden
- Oscar Arias Sanchez
- Oscar Clendenning Hammerstein II
- Oscar Handlin
- Oscar Levant
- Oscar Lewis
- Oscar Luigi Scalfaro
- Oscar Niemeyer Soares Filho
- Oscar Peterson
- Oscar Robertson
- Oscar Wilde
- Osceola
- Osip Emilyevich Mandelstam
- Oskar Lafontaine
- Osman I
- Ossip Joselyn Zadkine
- Osvaldo Aranha
- Oswald Garrison Villard
- Oswald Theodore Avery
- Oswaldo Gonçalves Cruz
- Oswaldo Lopez Arellano
- Othniel Charles Marsh
- Ottmar Mergenthaler
- Otto Graf Lambsdorff
- Otto Graham
- Otto Hahn
- Otto I
- Otto III
- Otto Lilienthal
- Otto Mueller
- Otto Paul Hermann Diels
- Otto Rank
- Otto Robert Frisch
- Otto Von Guericke
- Otto Wagner
- Otto of Freising
- Otto von Bismarck
- Otto von Gierke
- Otto von Kotzebue
- Ottobah Cugoano
- Ottorino Respighi
- Ou-yang Hsiu
- Ousmane Sembène
- Oveta Culp Hobby
- Ovid
- Owen Bieber
- Owen Glendower