Thomas Stucley (both: styōō´klē), 1525?–1578, English adventurer. He was rumored to be an illegitimate son of Henry VIII. He was in the service of Edward Seymour, duke of Somerset, and fled to France after Somerset's fall (1549). There he gained the favor of Henry II of France, who sent him (1552) on a mission to England. Stucley betrayed the projected French invasion of Calais but was imprisoned. Released in 1553, he joined the army of Emmanuel Philibert, duke of Savoy, in Flanders and took part in the battle of Saint-Quentin (1557). In 1563 Stucley organized a privateering expedition with Jean Ribaut under the cover of helping to colonize Florida and with surreptitious aid from Queen Elizabeth I. The resulting complaints of foreign nations caused Elizabeth to arrest him in 1565, but he was immediately pardoned. Stucley then went to serve in Ireland and in 1566 purchased the title of marshal of Ireland. Elizabeth, who distrusted him, refused to recognize this title, and in 1569 he was accused of treason. Stucley fled (1570) to Spain, where he was received at court, knighted, and recognized as duke of Ireland. He planned a Spanish invasion of Ireland but fell from favor at Madrid. His conduct at the battle of Lepanto (1571), where he commanded three ships, brought Stucley back into favor with the Spanish, and he continued plotting against England. In 1577 he received aid from Pope Gregory XIII for an invasion of Ireland. He set sail but at Lisbon was persuaded to join the Portuguese expedition of King Sebastian against Morocco and was killed at the battle of Ksar el Kebir. His adventures have been the subject of ballads and plays.