Boyd, real name William Millar, was born on American Independence Day of July 4, 1931, one of nine children of his Ulster mother and Canadian father.
On leaving Ballyclare High School, he studied book-keeping and found himself a job in an insurance office and later a travel agency. In the evenings and weekends, however, he treaded the boards with local theatre companies such as the Ulster Theatre Group in Belfast.
His attempts to break onto the professional scene met with little success initially, and even after moving to London he was forced to take a series of odd jobs - even including busking - while waiting for his big break.
A chance encounter with Sir Michael Redgrave, however, led to him being offered the role of leading man and director with the Arts Council of Great Britain repertory company.
That opportunity resulted in him being offered work by the BBC, with Boyd appearing in a number of television plays.
In 1956 he was signed up by 20th Century-Fox and, aged 25, appeared in the film The Man Who Never Was. It was another three years later, however, before the movie was released that was to make his name - and win him a Golden Globe - the classic Ben-Hur, in which he played opposite Charlton Heston.
Standing 6ft 1in tall and acknowledged as one of the best looking men to have graced the screen, he romanced on screen a host of leading ladies, including Brigitte Bardot, Sophia Loren, Doris Day and Gina Lollobrigida.
There were others who got away, however, and who might have pushed his career in a different direction. He was to have played Mark Antony opposite Elizabeth Taylor's Cleopatra, for instance, but opted to take another part after filming was delayed - with the role going to Richard Burton.
Boyd was also the original choice to play James Bond 007 in Dr No opposite Ursula Andress, but declined the part, which subsequently went to Sean Connery.
After more than a decade of box office success, including the likes of the science fiction favourite Fantastic Voyage, made in 1966, in which he, one of the crew of scientists, was miniaturised and injected into a human body, his career began to fade.
He told the magazine Photoplay: "They tried to make me a star, a leading man. Well, I'm not a star even though they thought I looked like one. I'm a character actor. When I've had the choice I've always opted for the character role. I'd rather be the pillar that holds up the star than the star himself."
Boyd, who made more than 50 films in total including many historical epics, wed twice but each of the marriages lasted less than a year.
The first was to a movie executive, Mariella di Sarzana, in 1958. The second marriage was to his personal assistant and secretary, Elizabeth Mills, who he had known since the 1950s.
They tied the knot just 10 months before Boyd dropped dead, on June 2, 1977, on a California golf course from a massive heart attack - just a month short of his 46th birthday.