Siegfried Rudolf Geißler (26 March 1929 – 10 July 2014) was a German composer, conductor, hornist and politician. He founded the Thüringen Philharmonie Suhl in 1979. After the Wende, he was a member of the New Forum who was elected to the first Landtag of Thuringia in 1990. As its senior, he was its Father of the House and opened the inaugural session.