Thomas Southwell may refer to:
Thomas Southwell (priest) (fl. 1420s–1440s), Canon of Windsor Thomas Southwell (died 1568), English landowner and courtier Thomas Southwell (died 1643), English landowner Thomas Southwell (Jesuit), pseudonym of Thomas Bacon (1592–1637), English-born Jesuit priest, teacher, and theologian Sir Thomas Southwell, 1st Baronet (died 1680), Anglo-Irish politician Thomas Southwell, 1st Baron Southwell (1665–1720), Irish MP for Limerick County 1695–1713 and 1715–1717, Commissioner of the Revenue Thomas Southwell, 2nd Baron Southwell (1698–1766), his son, Irish MP for Limerick County 1717–1720 Thomas Southwell, 1st Viscount Southwell (1721–1788), his son, Irish MP for Enniscorthy and Limerick County 1761–1766 Thomas Southwell, 2nd Viscount Southwell (1742–1796), his son, Irish MP for Limerick County 1767–1780 Thomas Southwell, 3rd Viscount Southwell (1777–1860), his son, Irish peer Thomas Southwell, 4th Viscount Southwell (1836–1878), his nephew, Irish Lord Lieutenant of Leitrim Thomas Southwell (1813–1881), pioneer of the Australian Capital Territory, see Weetangera, Australian Capital Territory Thomas Southwell (zoologist) (1879–1962), British zoologist