McCallum won a new generation of fans by starring in the popular series "NCIS".
The Scotland-born actor to musician parents has made a long acting career over 7 decades, starting with his days at the Royal London Academy of Dramatic Art in the fifties.
He began his career with minor roles in a number of British films, including Night to Remper (1958), in which he portrayed the radio operator aboard the Titanic.
He captured the attention of American audiences with a small but important role as one of the prisoners of war planning a mass escape from a German prison during World War II in the famous classic film The Great Escape in 1963.
McCallum was nominated for two Emmy Awards for his role in "A Man from UNCLE."
MGM said the late actor received more fan mail than any other star in the company's celebrity history.