William Ritchie Sorley (4 November 1855- 28 July 1935) was a British philosopher. He was one of the British Idealist school of thinkers, with interests in ethics.

He was Knightbridge Professor of Philosophy in the University of Cambridge from 1909 until 1933.

He is now remembered for his A History of British Philosophy to 1900, with its idiosyncratic slant, as a retrospective view from the point of view of British Idealism. The poet Charles Sorley was his son.