Mark Harmon

A. In the late eighties he was part of the cast of the Canadian premier of Key Exchange. In 1978 he appeared in three episodes of the acclaimed mini-series Centennial as Captain John MacIntoshan honorable Union cavalry officer.

Since 2003 Harmon has starred as Leroy Jethro Gibbs in the hit CBS series NCIS. Thomas Mark Harmon (born September 2 1951) is an American actor.