Sir William Hamilton KB, PC, FRS, FRSE (December 13, 1730 – April 6, 1803) is a British diplomat, antiquarian, archaeologist and vulcanologist.

After a short period as a Member of Parliament, he serves as British Ambassador to the Kingdom of Naples from 1764 to 1800.

He studies the volcanoes Vesuvius and Etna, becoming a Fellow of the Royal Society and recipient of the Copley Medal.

His second wife is Emma Hamilton, famed as Horatio Nelson's mistress.