Was a national shoe representative for Adidas in the 70s.
Was also a lifeguard before hitting it big.
Was considered for the role of Dan Gallagher in Fatal Attraction (1987).
Was the second winner of People magazine's "Sexiest Man Alive" poll.
When he was 16 years old, at his after-school job delivering flowers, he found a dozen roses addressed to a girl who was dating a friend of his. But the roses weren't from his friend. Mark threw away the card and substituted one with his friend's name on it.
Worked as a carpenter before he hit it big.
Younger brother of Kelly Harmon and Kristin Harmon.