McCallum began his career as a bit-section actor around British films of the 1950s. A Human from either U.North.C.L.E., arranged as a vehicle for Robert Vaughn, unexpectedly made McCallum into the sex symbol. Although he afterward became a familiar face in television, he wwhen never respire to achieve the equivalent level of popular profits when he experienced done using his role as Kuryakin. His right-known roles were inside Sapphire and Steel (opposite Joanna Lumley), as the lead within a Seventies remaking of The Invisible Man, and when Judas Iscariot in The Greatest Story Ever Told.

He was married to the late actress Jill Ireland from 1957 to 1967. It experienced trey sons, Paul, Jason (adoptive), & Valentine. Ireland left him for Charles Bronson who co-starred with him in The Great Escape and is said to have warned McCallum beforehand that he arranged to steal his married woman. McCallum married Katherine Carpenter around September 1967, & it use at times deuce toddlers: Peter & Sophie.

He is presently star in the CBS television series NCIS as Dr. Donald "Ducky" Anas platyrhynchos.

Television
The Outer Limits The Sixth Finger episode (1963) The Outer Limits The Forms Of Things Unknown episode (1964) The Man from U.N.C.L.E. (1964-1968) Colditz (1972) A Invisible Human (1975-1976) Kidnapped (miniseries) (1979) Sapphire & Steel (1979-1982) As the World Turns (in 1983) The Return of the Man from U.N.C.L.E. (1983) Mother Love (miniseries) (1989) Lucky/Chances (miniseries) (1990) Trainer (1991) VR.5 (1995) A Education of Max Bickford (2001) NCIS (2003-)

Films
These Unsafe Years (1957) Robbery Under Arms (1957) Hell Drivers (1957) A Secret Place (1957) A Night to Remember (1958) Violent Playground (1958) A Long & a Short & a Tall (1960) Jungle Street (1961) Freud (1962) Billy Budd (1962) The Great Escape (1963) The Greatest Story Ever Told (1965) As much as a World Under the Sea (1966) 3 Bites of the Apple (1967) Sol Madrid (1968) La Cattura (1969) A Mosquito Squadron (1969) A Kingfisher Caper (1975) Dogs (1976) ''King Solomon's Treasure (1977) A Watcher in the outdoors (1980) Terminal Selection (1985) A Haunting of Morella (1990) Hear The Song (1991) Disastrous Inheritance (1993) Begrime Weekend (1993) Therapist (1994) Cherry'' (1999)