Peter Michael Neumann OBE (born 28 December 1940) is a British mathematician. He is a son of the mathematicians Bernhard Neumann and Hanna Neumann and, after gaining a B.A. from The Queen's College, Oxford in 1963, obtained his D.Phil from Oxford University in 1966.
Neumann was a Tutorial Fellow at the Queen's College, Oxford and a lecturer at Oxford University. After retiring in 2008, he became an Emeritus Fellow at the Queen's College. His work has been in the field of group theory. He is also known for solving Alhazen's problem in 1997. Neumann's work in the history of mathematics includes a book, published in 2011, on the work of the short-lived French mathematician Évariste Galois (1811–1832).
In 1987, Neumann won the Lester R. Ford Award of the Mathematical Association of America for his review of Harold Edwards' book Galois Theory.
In 2003, the London Mathematical Society awarded him the Senior Whitehead Prize. He was the first Chairman of the United Kingdom Mathematics Trust, from October 1996 to April 2004, succeeded by Bernard Silverman. He was appointed Officer of the Order of the British Empire (OBE) in the 2008 New Year Honours.