Mark Harmon

Thomas Mark Harmon (born September 2, 1951) is an American stand-up comedian, actor, voice actor, television host, filmmaker, producer and director. He has appeared in a wide variety of roles since the early 1970s.

Harmon gained recognition for portraying Secret Service special agent Simon Donovan in The West Wing,[2] receiving a 2002 Emmy Award nomination for his acting in the four-episode story arc.[3]

Harmon was cast in a similar role a year later:[4] Donald P. Bellisario—the creator of both JAG and NCIS for CBS—had seen Harmon in The West Wing and decided to cast him in NCIS.[5] Harmon's character of NCIS special agent Leroy Jethro Gibbs was first introduced in a guest starring role in two episodes of JAG.[4] Since 2003, Harmon has starred in NCIS as the same character.[4]