Kidd, William (1645?–1701), a Scottish shipowner and alleged pirate. Originally commissioned a privateer, Kidd apparently crossed the narrow line separating privateering from piracy. Some historians, however, view him as a victim of circumstances. His execution resulted largely from a political struggle between some members of England's ruling Whig party, who had employed him, and the Tory party.

Kidd was born in Scotland, the son of a clergyman. He became a shipowner and sea captain and was living in the colony of New York by 1690. In 1695 he was given two commissions at the request of members of the Whig government, who were to be his anonymous financial backers and who were to share in his booty. One commission, from King William III, was to crush piracy in the Indian Ocean; the other, from the English admiralty, was to seize booty from England's enemies, particularly France.

His expedition, which sailed under an agreement that there would be no pay unless prizes (ships) were taken, was plagued with difficulties. No ships were taken during the first year at sea, a third of the crew died of cholera, and the remaining crewmen nearly mutinied. At this point Kidd began attacking ships whose status, in relation to his commissions, was questionable. English authorities soon received complaints from plundered vessels, and Kidd, who became an embarrassment to the Whigs, was declared a pirate. He surrendered in 1699 at New York City on the promise of a pardon, but was sent to London for trial.

Kidd presented a strong defense of his actions, but was tried before a court predisposed by the political situation to find him guilty. He was convicted and in 1701 was hanged at Execution Dock on the Thames River waterfront. His body was left hanging in view of every ship as a warning.

Soon after Kidd's arrest, a small quantity of booty believed to be his was found on Gardiners Island, off the east coast of Long Island. Since then people have combed the area looking for the rest of Captain Kidd's buried treasure. Various rumors concerning the treasure formed the basis of Robert Louis Stevenson's novel Treasure Island, Edgar Allan Poe's short story “The Gold Bug,” and other works of fiction.