Oskar Luts (7 January 1887 [O.S. 26 December 1886] – 23 March 1953) was an Estonian writer and playwright.

Oskar Maria Graf was a German-American writer who wrote several narratives about life in Bavaria, mostly autobiographical. In the beginning, Graf wrote under his real name Oskar Graf. After 1918, his works for newspapers were signed with the pseudonym Oskar Graf-Berg; only for those of his works he regarded as "worth reading", he used the name Oskar Maria Graf.

Oskar Reinhard Negt is a philosopher and critical social theorist. He is an emeritus professor of sociology at Leibniz University Hannover, and one of Germany's most prominent social scientists. Little of his work has been translated into English.

Leopold Hermann Oskar Panizza was a German psychiatrist and avant-garde author, playwright, novelist, poet, essayist, publisher and literary journal editor. He is best known for his provocative tragicomedy, Das Liebeskonzil, for which he served a one-year prison sentence after being convicted in Munich in 1895 on 93 counts of blasphemy. Upon his release from prison, he lived for eight years in exile, first in Zürich and later in Paris.

Oskar Pastior was a Romanian-born German poet and translator. He was the only German member of Oulipo.

Oskar Schade was a German philologist and Germanist born in Erfurt.

Oskar Seyffert was a German art professor at the Königliche Kunstgewerbeschule in the Kingdom of Saxony.

Oskar Freiherr von Redwitz was a German poet from Lichtenau, Bavaria. Having studied at the universities of Munich and Erlangen, he was apprenticed to the law in the Bavarian State service (1846–49).

Osman Mirzayev was a journalist, writer and publicist in Soviet Azerbaijan, then part of the USSR. The journalist is the father of Sevinj Osmanqizi.

Osmo Tapio Jussila (14 March 1938 in Haukipudas – 15 March 2019), was a Finnish historian.