Pierre Klossowski (August 9, 1905 in Paris – August 12, 2001 in Paris) was a French writer, translator and artist. He was the eldest son of the artists Erich Klossowski and Baladine Klossowska, and his younger brother was the painter Balthus. Michel Foucault noted in a letter that Klossowski's book La Monnaie vivante is the most sublime book of our era.
Born in Paris, Pierre Klossowski was the older brother of the artist Balthazar Klossowski, better known as Balthus. Their parents were the art historian Erich Klossowski and the painter Baladine Klossowska. His German-educated father came from a family supposedly belonging to the former Polish petty nobility (drobna szlachta) and bearing the Rola coat of arms. His mother, Baladine Klossowska, was born as Elisabeth Dorothea Spiro in Breslau, Prussia (now Wrocław, Poland).
He was responsible for a new publication of The 120 Days of Sodom & Other Writings by Marquis de Sade in 1964.
When he was 18, Pierre was André Gide's secretary and worked on the drafts of Les faux-monnayeurs for him.
Pierre Klossowski wrote full length volumes on the Marquis de Sade and Friedrich Nietzsche, a number of essays on literary and philosophical figures, and five novels. Roberte Ce Soir (Roberte in the Evening) provoked controversy due to its graphic depiction of sexuality. He translated several important texts (by Virgil, Ludwig Wittgenstein, Martin Heidegger, Friedrich Hölderlin, Franz Kafka, Nietzsche, and Walter Benjamin) into French, worked on films and was also an artist, illustrating many of the scenes from his novels. Klossowski participated in most issues of George Bataille's review, Acéphale, in the late 1930s.