Sir Richard Mayne KCB (27 November 1796 - 26 December 1868) was a barrister and the joint first Commissioner of Police of the Metropolis, the head of the London Metropolitan Police (1829-1868). With an incumbency of 39 years, he was also the longest-serving Commissioner in the force's history, as well as the youngest on his appointment.

Mayne was born in Dublin, the son of Judge Edward Mayne. He gained his BA from Trinity College, Dublin in 1818 and his MA from Trinity College, Cambridge, in 1821. He was called to the Bar at Lincoln's Inn on 9 February 1822 and commenced practice on the Northern Circuit.