Robertson was a prolific, gifted and successful actor who first hit his stride in the 1950s. Among his most notable roles was his star turn as a young John F. Kennedy in the World War II drama PT 109, which was filmed while Kennedy was president.
In 1957, Robertson married Cynthia Stone, and they had a daughter, Stephanie, before splitting in 1960. In 1966, he married actress and Post cereal heiress Dina Merrill with whom he had a daughter, Heather. The couple divorced in 1989.
Robertson's funeral is set for Friday in East Hampton.
