Sir William St Leger PC (Ire) (1586–1642) was an Anglo-Irish landowner, administrator and soldier, who began his military career in the Eighty Years' War against Habsburg Spain. He settled in Ireland in 1624, where he was MP for Cork County in two Irish parliaments and Lord President of Munster. During the Irish Rebellion of 1641, he played a leading part in suppressing the rising in Munster before dying in 1642.