Oskar Reinhart (11 June 1885 – 16 September 1965) was a Swiss art collector and patron from Winterthur. After a career in the family’s trading business, he devoted himself to building a collection of European art with a focus on French Impressionism and Swiss painting. His collections, today housed at the Museum Oskar Reinhart am Stadtgarten and the Römerholz estate, are open to the public.