Jethro Gibbs is a fictional character from the television series NCIS, portrayed by actor Mark Harmon. He serves as a special agent and the leader of the NCIS team, which investigates crimes involving the U.S. Navy and Marine Corps. Gibbs is known for his strong leadership skills, sharp instincts, and a no-nonsense approach to solving cases. Gibbs has a complex personality, often displaying a tough exterior while caring deeply for his team. He is characterized by his strict rules, particularly his famous "Gibbs' Rules," which guide his decisions and actions. Throughout the series, Gibbs' background as a former sniper and his experiences in the military shape his character and methods.