His real name is William Millar and he was born on July 4th, 1931 from a family of nine children who lived in the poorest part of Belfast (Northern Ireland).
He was 8 when he was chosen, among a gang of street kids, to take part in a radio show. Under the maiden name of his mother, Martha Boyd, he got some theatre parts (especially backstage !).
At the age of 17, he went to Liverpool and then to London. He found some little jobs to survive and sang some Irish ballads for people queueing in front of cinemas and theatres in the West End.
He was at last noticed by Michael Redgrave who allowed him to start his career as an actor.
In August 1958, he married Mariella di Sarzana, a beautiful Italian woman who was a press attaché on the filming of Ben-Hur. But they got divorced only 7 months later in March 1959.
He later decided to become an American citizen. He became one on December 22nd, 1963. At the welcome party given by his Hollywood friends, he frowned at the decoration on the party cake that read, "He's Our Steve - Ex-Irishman !" He then said : "Sure, I'm on this side now, but that's one thing you can never ex out of a Belfast blatherskite whose daddy came from the County Kerry." (from Screen Stories, April 1964).
When he settled in Tarzana, in California, he tried to have some of his family settle there with him as for example his brother Alex. But they preferred to remain in Ireland.
All along his life, he had many love affairs with famous actresses but preferred to remain a bachelor, seeing his marriage with Mariella as a mistake. However at the end of his life, he married his secretary, Elizabeth Mills, who was his best friend since she had helped him in 1955 when he was starving in London.
He died on June 2nd, 1977 from a heart attack, while playing golf. He was buried in Tarzana (USA).
Here is a map to see where his tomb in Oakwood is.