David Keith McCallum (born September 19, 1933, in Glasgow, Scotland) is a Scottish-American actor, best known for his roles on the NBC adventure series The Man from U.N.C.L.E. and The Invisible Man. He was the voice of Paradox in Cartoon Network Universe: FusionFall.
Since David McCallum's father, David McCallum Sr., was first violinist for the London Philharmonic and his mother, Dorothy Dorman, was a cellist, it's not surprising that David was originally headed for a career in music, playing oboe. He studied briefly at the Royal Academy of Music. He left that, however, for the Royal Academy of Dramatic Art.
He made nearly a dozen movies in the United Kingdom before his critically acclaimed work as Lt. Wyatt in Billy Budd (1962). To the older generation, he is perhaps best known for his portrayal of U.N.C.L.E. agent Ilya Kuryakin in the hit TV series The Man from U.N.C.L.E. (1964). To younger audiences, he is best known for his superlative portrayal of Dr. Donald "Duckie" Mallard on the hit CBS series NCIS (2003).