Pierre Klossowski (/kləˈsɒfski/; French: [klɔˈsɔfski]; August 9, 1905, Paris – August 12, 2001, 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.
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).