William Trevor Thomas (8 March 1907 – 3 February 1969), also known by the nickname of "Ocker", was a Welsh dual-code international rugby union, and professional rugby league footballer who played in the 1930s and 1940s. He played representative level rugby union (RU) for Wales, and at club level for Abertillery RFC, as a flanker, i.e. number 6 or 7, and representative level rugby league (RL) for Wales, and at club level for Oldham (Heritage No. 281) (two spells) (captain), and Wigan (Heritage No.), as a second-row, i.e. number 11 or 12, during the era of contested scrums.