Sir Humphrey Gilbert (c. 1539 – 9 September 1583) of Devon in England was a half-brother (through his mother) of Sir Walter Raleigh.Adventurer, explorer, member of parliament, and soldier, he served during the reign of Queen Elizabeth and was a pioneer of English colonization in North America and the Plantations of Ireland.

Gilbert was the fifth son born to Otho Gilbert of Compton and Greenway, Galmpton, Devon, by his marriage to Katherine Champernowne. His brothers Sir John Gilbert and Adrian Gilbert, and his half brothers Carew Raleigh and Sir Walter Raleigh, were also prominent during the reigns of Queen Elizabeth I and King James. Katherine was a niece of Kat Ashley, Elizabeth's governess, who introduced her young kinsmen to the court. Gilbert's uncle, Sir Arthur Champernowne, involved him in efforts to establish plantations in Ireland between 1566 and 1572.

Sir Henry Sidney became Gilbert's mentor, and he was educated at Eton and the University of Oxford, where he learned to speak French and Spanish and studied the arts of war and navigation. He went on to reside at the Inns of Chancery in London in about 1560–1561.