Rush Rhees (/riːz/; 19 March 1905 – 22 May 1989) was an American philosopher. He is principally known as a student, friend, and literary executor of the philosopher Ludwig Wittgenstein. With G. E. M. Anscombe, he edited Wittgenstein's posthumous Philosophical Investigations (1953), a highly influential work. He was also responsible for publishing other works by Wittgenstein, including Remarks on the Foundations of Mathematics, Philosophische Bemerkungen, Philosophical Remarks, and Philosophical Grammar. Rhees taught at Swansea University from 1940 to 1966.
Rush Rhees was born in the United States of America on 19 March 1905, at Rochester, New York. He was the son of Benjamin Rush Rhees, a Baptist minister, author and president of the University of Rochester. He studied philosophy at the University of Rochester, but was expelled in 1922 for insolent questions. In 1924 he moved to Britain, where he graduated from the University of Edinburgh in 1928. In 1932 he became a research fellow at the University of Cambridge. There he impressed G. E. Moore who described him as his ablest student, and met Wittgenstein, who became a close friend, and continued to visit him after his move to Swansea in Wales.
Rhees taught philosophy at Swansea University from 1940 to 1966. He has been known mainly as a Wittgenstein exegete and for his influence on his friends, colleague Peter Winch and former student and his literary executor D. Z. Phillips. He was responsible for editing but also developing the legacy left by Wittgenstein, at times emphasising religious and ethical understandings of Wittgenstein's work, reflecting how Wittgenstein himself sometimes said he wanted to be understood. Together with G. H. von Wright and G. E. M. Anscombe he was appointed by Wittgenstein as his literary executor. He was also Wittgenstein's personal executor.