William Willoughby

William Willoughby may refer to:


 * William Willoughby, 11th Baron Willoughby de Eresby (1482–1526), father of Katherine Willoughby and the largest landowner in Lincolnshire, England
 * William Willoughby, 1st Baron Willoughby of Parham (c. 1515–1570), English baron and nephew of the above
 * William Willoughby (c.1566-1615), MP for Nottingham
 * William Willoughby, 3rd Baron Willoughby of Parham (1584–1617), English peer
 * William Willoughby, 6th Baron Willoughby of Parham (c. 1616–1673), English landowner and politician
 * William Willoughby, 5th Baron Willoughby de Eresby (c. 1370–1409), English baron
 * William Arnson Willoughby (1844–1908), Ontario physician and political figure
 * William F. Willoughby (1867–1960), author of public administration texts
 * Bill Willoughby (born 1957), American former basketball player
 * Bill Willoughby, American conservationist