William Gregg

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