Sir William Thompson or Thomson may refer to: Sir William Thompson (1614–1681) (1614–1681), of London, English businessman and politician Sir William Thompson (Ipswich MP) (1678–1739), of Middle Temple, an English judge and Whig politician William Thomson, 1st Baron Kelvin (1824–1907), British mathematical physicist and engineer Sir William Thompson (physician) (1861–1929), Irish physician