The 20th season of NCIS premiered without Mark Harmon, who played iconic special agent Leroy Gibbs. This is the first time the show has aired without him. In the fourth episode of Season 19, Gibbs left his job and decided to live a peaceful life in Alaska. Although Harmon has left the show, there is a chance he may return for a specific episode in the future. Despite not reprising his role, Harmon is still an executive producer of the show. Fans were surprised not to see his name in the credits for Season 20, but he may make a cameo appearance in Season 21 or 22.