Sir William Fownes, 2nd Baronet

Sir William Fownes, 2nd Baronet (1709 – 5 June 1778) was an Anglo-Irish politician.

Fownes was the son of Sir William Fownes, 1st Baronet, and in 1735 he inherited his father's baronetcy. Fownes was the Member of Parliament for Dingle in the Irish House of Commons between 1749 and 1760, before representing Knocktopher from 1761 to 1776. Fownes was admitted to the Irish Privy Council in 1761. He finally represented the borough of Wicklow between 1776 and his death in 1778.

In 1739, William married Lady Elizabeth Ponsonby. His granddaughter was Marianne-Caroline Hamilton via his daughter and only child Sarah Tighe (née Fownes).