David McCallum (September 19, 1933 – September 25, 2023) was a Scottish actor and musician, based in the United States. 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 (1964–1968).
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 chief medical examiner Dr. Donald "Ducky" Mallard in the CBS television series NCIS, which he played for 20 seasons until his death in 2023. In film roles, McCallum notably appeared in The Great Escape (1963) and as Judas Iscariot in The Greatest Story Ever Told (1965).
He appeared in two episodes of the original series from 1963 to 1964:
- "The Sixth Finger" - Gwyllm Griffiths
- "The Forms of Things Unknown" - Tone Hobart
In 1997, he played Joshua Hayward in the revival series episode "Feasibility Study", itself a remake of the original series episode "A Feasibility Study".
Along with Leonard Nimoy, Cliff Robertson, Barbara Rush (who appeared with him in "The Forms of Things Unknown") and Peter Breck, he was one of only five actors to appear in both the original and revival series of The Outer Limits.