John Joseph Patrick Ryan (December 30, 1920 – January 21, 1998), best known by his stage name Jack Lord, was an American television, film, and Broadway actor. He was best known for his starring role as Steve McGarrett in the American television program Hawaii Five-O from 1968 to 1980. Lord also appeared in several classic feature films earlier in his career, among them Man of the West (1958) starring Gary Cooper and the first James Bond film Dr. No (1962) starring Sean Connery.

Born in Brooklyn, New York, Jack Lord was the son of Irish-American parents. His father, William Lawrence Ryan was a steamship company executive. He developed his equestrian skills on his mother's fruit farm in the Hudson River Valley. At the age of fifteen he started spending summers at sea, and from the deck of cargo ships, painted and sketched the landscapes he encountered — Africa, the Mediterranean and China. He was educated at John Adams High School in Ozone Park, New York, Fort Trumbull United States Merchant Marine Academy, then located in New London, Connecticut, graduating as an Ensign with a Third Mates License.

He attended New York University on a football scholarship, and earned a degree in Fine Arts. He spent the first year of World War II with the War Department's Corps of Engineers, building bridges in Persia. He then returned to the Merchant Marine as an Able Seaman before enrolling in the deck officer course at Fort Trumbull. While making maritime training films, he took to the idea of acting.