Family spokesperson Jeff Ballard said Conrad died Saturday morning in Malibu, California, from heart failure.
With his good looks and strong physique, Conrad was a rising young actor in the late 1950s and was chosen for the lead in “Hawaiian Eye.” He became an overnight star after the show debuted in 1959.
Conrad had a reputation as a tough customer and was sued more than a half-dozen times as a result of fistfights. Playing himself in a 1999 episode of the TV series “Just Shoot Me,” he lampooned his threatening, tough-guy persona. He was also featured in 1970s commercials for Eveready Batteries, with a battery on his shoulder, a menacing stare and a popular catchphrase, “I dare you to knock this off.”