was a German composer of contemporary classical music and an academic teacher based in Karlsruhe. He was an influential post-war European composer, as "one of the most original and independent musical voices" there, composing over 500 works including several operas.

The premiere of Rihm's Morphonie for orchestra at the 1974 Donaueschingen Festival won him international recognition. Rihm pursued a freedom of expression, combining avant-garde techniques with emotional individuality. His chamber opera Jakob Lenz was premiered in 1977, exploring the inner conflict of a poet's soul. The premiere of his opera Oedipus at Deutsche Oper Berlin in 1987 was broadcast live and recorded as DVD. When his opera Dionysos was first performed at the Salzburg Festival in 2010, it was voted World Premiere of the Year by Opernwelt. He was commissioned to compose a work for the opening of the Elbphilharmonie, and created the song cycle Reminiszenz which was premiered in 2017.

Rihm was professor of composition at the Hochschule für Musik Karlsruhe from 1985, with students including Rebecca Saunders and Jörg Widmann. He was composer in residence for the BBC, at the Lucerne Festival and the Salzburg Festival. He was honoured as an officer of the Ordre des Arts et des Lettres in 2001 and received the Ernst von Siemens Music Prize in 2003.