Paul Kingsley Townsend (; born 3 March 1951) is a British physicist, currently a Professor of Theoretical Physics in Cambridge University's Department of Applied Mathematics and Theoretical Physics. He is notable for his work on string theory.
He received his PhD from Brandeis University in 1976 for his dissertation The 1/N expansion of scalar field theories supervised by Howard Joel Schnitzer. Since then he has over 320 publications.
In 1987, , , and Paul Townsend showed that there are no superstrings in eleven dimensions (the largest number of dimensions consistent with a single graviton in supergravity theories), but supermembranes. In 1977 he was the first to formulate pure 4D N = 1 supergravity in anti-de Sitter space.
He was elected a Fellow of the Royal Society in May 2000.