Olga Maria ('Olly') Donner was a Swedish-speaking Finnish writer and anthroposopher, known also by her pen name Jean Bray.

Olof Celsius was a Swedish botanist, philologist and clergyman. He was a professor at Uppsala University, Sweden. Celsius was a mentor of the botanist and scientist Carl Linnaeus. Celsius wrote his most famous book on biblical plants, Hierobotanicon, in 1745–47. Celsius was also a prominent runologist.

Olof Gustaf Hugo Lagercrantz was a Swedish writer, critic, literary scholar and publicist.

Olof von Dalin was a Swedish nobleman, poet, historian and courtier. He was an influential literary figure of the Swedish Enlightenment.

Dame Olwen Hufton, is a British historian of early modern Europe and a pioneer of social history and of women's history. She is an expert on early modern, western European comparative socio-cultural history with special emphasis on gender, poverty, social relations, religion and work. Since 2006 she has been a part-time Professorial Research Fellow at Royal Holloway, University of London.

Olyk Ipai (Mari: О́лык Ипа́й; 24 March 1912 – 11 November 1937) was a Mari poet.

Olympe Bhêly-Quénum is a Beninese writer, journalist and magazine editor. He is the nephew of anthropologist Maximilien Quenum-Possy-Berry.

Olympe de Gouges was a French playwright and political activist. She is best known for her Declaration of the Rights of Woman and of the Female Citizen and other writings on women's rights and abolitionism.

Olympiodorus the Younger was a Neoplatonist philosopher, astrologer and teacher who lived in the early years of the Byzantine Empire, after Justinian's Decree of 529 AD which closed Plato's Academy in Athens and other pagan schools. Olympiodorus was the last pagan to maintain the Platonist tradition in Alexandria ; after his death the School passed into the hands of Christian Aristotelians, and was eventually moved to Constantinople. He is not to be confused with Olympiodorus the Deacon, a contemporary Alexandrian writer of Bible commentaries.

Olzhas Omaruly Suleimenov is a Kazakh former Soviet dissident, Russian-language poet, Turkologist, politician, and anti-nuclear activist.