(Born Sept. 02, 1951) Mark Harmon is an American actor. He is currently the star of the CBS series NCIS. He portrayed doctors in two previous series, Dr. Jack McNeil on Chicago Hope and Dr. Bobby Caldwell on St. Elsewhere. In a limited engagement on Moonlighting, Harmon, along Cybill Shepherd and Bruce Willis, helped create one of the hottest television triangles in recent memory. One of his more famous movie roles was as Mr. Freddy Shoop in Summer School.