William Back (c. 1856 – 15 February 1911) was an Australian cricketer who played at first-class level for Western Australia in 1893, including in its inaugural first-class match. Born on Rottnest Island, Back played for Fremantle in the WACA grade cricket competition, and led the league's batting averages during the 1887–88 season, scoring 267 runs from ten innings at an average of 53.50. His only state-level matches played during Western Australia's tour of the eastern colonies in early 1893. He opened the batting for the side in both of its two first-class matches on the tour, against South Australia and Victoria, variously partnering with Percival Hussey, , and Ernest Randell. In the first match, Back scored four and seven runs, and in the second match, a duck and one run, with Western