William Roy (1726–1790) was a Scottish military engineer, surveyor, and antiquarian.
William Roy may also refer to:
William Roy (medium) (1911–1977), notorious fraud medium in the history of British spiritualism William Roy (pole vaulter) (born 1914), American pole vaulter, 3rd at the 1935 USA Outdoor Track and Field Championships William R. Roy (1926–2014), United States representative from Kansas
Bill Roy Jr. (born 1954), American member of the Kansas state legislature and son of William R. Roy William Burton Roy (born 1958), retired USAF officer and Olympian sport shooter