Billy, Willie or William Forbes may refer to:
Financiers Sir William Forbes, 6th Baronet (1739–1806), Scottish banker William Forbes of Callendar (1756–1823), Scottish coppersmith and landowner William Howell Forbes (1837–1896), American businessman in Hong Kong William Hathaway Forbes (1840–1897), American investor in company owned by Alexander Graham Bell
Footballers Billy Forbes (Scottish footballer) (before 1895–after 1928), right back who also played in Massachusetts Willie Forbes (1922–1999), Scottish wing half Billy Forbes (footballer, born 1990), Turks and Caicos Islands striker
Public officials William Forbes (Lower Canada politician) (1787–1814), merchant and legislator William Forbes (MP) (1806–1855), Scottish MP for Stirlingshire William Henry Forbes (1815–1875), American fur trader and territorial legislator William Cameron Forbes (1870–1959), American diplomat and investment banker William Forbes (Talamancan king), King of Talamanca, Costa Rica between 1872 and 1880.
Scholars William Forbes (bishop) (1585–1634), Scottish churchman, first Bishop of Edinburgh William S. Forbes (1831–1905), American physician William Alexander Forbes (1855–1883), English zoologist William T. M. Forbes (1885–1968), American entomologist
Others William Forbes, 7th Lord Forbes (1513-1593), Scottish landowner William Nairn Forbes (1796–1855), British military engineer William Forbes (railway manager) (1856–1936), British railway manager William E. Forbes (1906–1999), member of the University of California Board of Regents William Garret Forbes (1751–1840), American silversmith
See also William Forbes Mackenzie (1807–1862), Scottish Conservative politician William Forbes Skene (1809–1892), Scottish historian and antiquary William Forbes Gatacre (1843–1906), British general William Forbes-Sempill, 19th Lord Sempill (1893–1965), British engineer