David Keith McCallum (19 September 1933 – 25 September 2023) was a Scottish actor and musician. He gained wide recognition in the 1960s for playing secret agent Illya Kuryakin in the television series The Man from U.N.C.L.E. His other notable television roles include Simon Carter in Colditz (1972–1974) and Steel in Sapphire & Steel (1979–1982). Beginning in 2003, McCallum gained renewed international popularity for his role as NCIS medical examiner Dr. Donald "Ducky" Mallard in the American television series NCIS, which he played for 20 seasons until his death. On film, McCallum notably appeared in The Great Escape (1963).
Source : Wikipedia