John Kevin Barry Coughlin was born in Inwood, Manhattan, New York, to John Joseph Coughlin and Marguerite O'Brien. He had an older sister, Joan Marie Coughlin Gaudet, a former nun with the Sacred Heart of Mary. The family lived at 45 Sickles Street in Manhattan until they moved to Rye, New York, around 1960.
Kevin began modeling at the age of 2 and made his television debut on his seventh birthday, December 12, 1952, on the show "Mama," where he remained a regular for four years. He starred in several TV dramas, including "A Trip to Czardis" and "The Ballad of Huckleberry Finn," which are now preserved at the Museum of Television and Radio.
Kevin attended Mace School and later studied theater at Northwestern University in Evanston, Illinois, from 1963 to 1967. He then moved to Hollywood, appearing in several youth culture movies and marrying Pamela Elaine. In 1972, he co-founded COLADD Productions with David Ladd and produced and hosted a TV talk-show, "The Age of Aquarius."
Kevin's film and television career seemed to end abruptly after he starred in the comedy "The Gay Deceivers" in 1969. His last known screen appearance was a small role on the TV show "Gunsmoke" in 1975. There were reports of him working on European films in the 1970s, but this was never confirmed.
Tragically, Kevin's life was cut short on January 10, 1976, when he was struck by a speeding car while cleaning his windshield on Ventura Boulevard. He was just 31 years old at the time of his death. Kevin had a lifelong struggle with clubfeet, but he never let it hold him back. He is buried at Gate of Heaven Cemetery in Hawthorne, New York, with the inscription "BELOVED BY ALL."