Leopold Eustachius Czapek (15 November 1792, ÃÂeský Krumlov, Bohemia â 1840, Iliria) was an Austrian pianist and composer. He was friends with Frédéric Chopin and corresponded regularly with him. Among his own compositions is a variation on a theme, a waltz by Anton Diabelli, for the Vaterländischer Künstlerverein.