Sir William Osborne, 8th Baronet, (d. 30 September 1783) was an Irish baronet and politician.
The son of Sir John Osborne, 7th Baronet and his wife Editha Proby, he succeeded in the baronetcy on 11 April 1743.
Osborne served as High Sheriff of County Waterford in 1750 and served as a Member of Parliament in the Irish House of Commons for Carysfort between 1761 and 1768, for Dungarvan between 1768 and 1783 and for Carysfort again in 1783, and was sworn of the Irish Privy Council in 1770.
Sir William Osborne married (lic. 20 March 1749) Elizabeth Christmas, daughter of Thomas Christmas MP, of Whitfield, Co. Waterford and Elizabeth Marshall, and had eight children: