William Gregg may refer to:
William Gregg (VC) (1890–1969), British First World War Victoria Cross recipient William Gregg (industrialist) (1800–1867), founder of the pioneer Graniteville, South Carolina textile mill William Gregg (tennis), Australian tennis player in 1907 Australasian Championships William Gregg (New Zealand businessman), founder of the New Zealand company Gregg's William Gregg (clerk and spy) (died 1708), Scottish clerk and spy Bill Gregg (1914–2000), Australian rules footballer William O. Gregg, American bishop William Gregg (theologian) (1817–1909), Canadian theologian and clergyman; Professor of Apologetics
See also William Greg (1809-1881), English essayist William Greig (disambiguation)