John Joseph Patrick Ryan, best known by his stage name, Jack Lord, was an American television, film and Broadway actor, director and producer. He starred as Steve McGarrett in the CBS television program Hawaii Five-O, which ran from 1968 to 1980.

Steve McGarrett is a fictional character who is the protagonist of CBS' Hawaii Five-O created by Leonard Freeman. McGarrett is a former United States Navy officer and the leader of a special state police task force, which is called Five-O. McGarrett was portrayed by actor Jack Lord in the original show from 1968 to 1980, and later by Alex O'Loughlin in the series' remake from 2010 to 2020. Throughout the show, McGarrett is partner to Detective Danny "Danno" Williams.