Who WAS Hugh O'Brian?

Hugh O'Brian, who has died, aged 91, was a handsome journeyman actor who had roles aplenty in the 1950s and '60s. Now largely forgotten, he was once noted for his insightful quip on the fleeting nature of fame. Using himself as an example, he said there were five crucial stages in an actor's career:

(1) “Who is Hugh O’Brian?”
(2) “Get me Hugh O’Brian as the star of our next picture!”
(3) “Get me somebody who’s a Hugh O’Brian type.”
(4) “Get me a young Hugh O’Brian.”
(5) “Who WAS Hugh O’Brian?”