David Keith McCallum Jr. (born 19 September 1933) is a British actor and musician. He first gained recognition in the 1960s for playing secret agent Illya Kuryakin in the television series The Man from U.N.C.L.E. and Later in Sapphire & Steel. In recent years, McCallum has gained renewed international recognition and popularity for his role as NCIS medical examiner Dr. Donald "Ducky" Mallard in the American television series NCIS. The Man from U.N.C.L.E., intended as a vehicle for Robert Vaughn, made McCallum into a sex symbol, his Beatle-style blond haircut providing a trendy contrast to Vaughn's clean-cut appearance. McCallum's role as the mysterious Russian agent Illya Kuryakin was originally conceived as a peripheral one. McCallum, however, took the opportunity to construct a complex character whose appeal rested largely in what was shadowy and enigmatic about him. Kuryakin's popularity with the audience and Vaughn's and McCallum's on-screen chemistry were quickly recognized by the producers, and McCallum was elevated to co-star status. McCallum never quite repeated the popular success he had gained as Kuryakin until NCIS, though he did become a familiar face on British television in such shows as Colditz (1972–74), Kidnapped (1978), and ITV's science-fiction series Sapphire & Steel (1979–82) opposite Joanna Lumley. In 1975 he played the title character in a short-lived U.S. version of The Invisible Man.