The son of a Heisman trophy winner, Thomas Mark Harmon followed in his father's football footsteps by becoming UCLA's starting quarterback. Following graduation and after considering careers in advertising or law, Mark opted to pursue his mother's line of work: acting. During his early years, he worked as a carpenter to make ends meet and spent a good decade taking on bit parts. His years of dedication paid off when Mark was cast as dreamy Doctor Bobby Caldwell on the hospital drama, St. Elsewhere. But Mark was determined to expand beyond his pretty boy image, and when he was offered the opportunity to play one of the first characters on TV to contract HIV, he embraced it fully. Over the years, he's managed to balance a successful career with a thriving family life with longtime wife, actress Pam Dawber. Today Mark shows no sign of slowing down. Playing special agent Jethro Gibbs on the popular drama NCIS, his career is hotter than ever.