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.

Hawaii Five-O is an American police procedural drama series produced by CBS Productions and created by Leonard Freeman. Set in Hawaii, the show originally aired for 12 seasons on CBS from September 20, 1968, to April 8, 1980, and continues in reruns. At the airing of its last episode, it was the longest-running police drama in American television history, and the last scripted primetime show that debuted in the 1960s to leave the air.