Hugh Osborn FRS is a British theoretical high-energy physicist and a professor emeritus at the University of Cambridge, Department of Applied Mathematics and Theoretical Physics.

Osborn obtained his PhD in 1967 from the University College London.

[2] In 1989, Osborn [3] obtained the first proof of the four-dimensional C-theorem, which was conjectured one year earlier by John Cardy.

Osborn's proof was applicable to renormalization group flows which are perturbative, that is do not deviate far from the free quantum field theories, and was valid to all orders in perturbation theory.

It provided a strong hint that the four-dimensional C-theorem must be universally valid, but a nonperturbative proof of this fact was found only in 2011 by Zohar Komargodski and Adam Schwimmer.