William Fennex (born c.1764 at Gerrards Cross, Buckinghamshire; died 4 March 1838 at Stepney, London) was a famous English cricketer. He was a noted all-rounder and right-arm underarm fast bowler who played major cricket from 1786 to 1816. As a batsman, Fennex was reputed to be one of the first to use forward play and was said to be a good driver of the ball. As a bowler, at a time when only underarm bowling was permitted, he was said to have the highest delivery of anybody, "his hand, when propelling the ball, being nearly on a level with his shoulder".