Mark Harmon is an American actor best known for portraying Special Agent Leroy Jethro Gibbs on the long-running television series NCIS. This relationship explainer clarifies who Mark Harmon is, how he came to play Gibbs, and how his performance shaped the show. It focuses on verified production details, onscreen contributions, and career context without speculation or rumor. The following sections break down his casting, character traits, and the lasting influence of this role on his public profile and the series.
