His father David McCallum Sr., was first violinist for the London Philharmonic and his mother, "Dorothy Dorman", was a cellist, so it is not surprising that he was originally headed for a career in music (oboe), studying briefly at the Royal Academy of Music. He left that, however, for the Royal Academy of Dramatic Art. McCallum was born in Glasgow, and was educated at University College School, a famous boys' independent school in Hampstead, London. He began his career as a bit-part actor in British films of the late-1950s and early-1960s. The Man from U.N.C.L.E., intended as a vehicle for Robert Vaughn, unexpectedly made McCallum into a sex symbol, his Beatle-style blonde haircut providing a trendy contrast with Vaughn's rather traditional appearance. Hero worship even led to a record, Love Ya, Illya, performed by Alma Cogan under the name Angela and the Fans ("I wish, I wish, I wish, I wish, I wish that Illya loved me"), which was a "pirate radio" hit in Britain in 1966.

Although McCallum subsequently became a familiar face on television, he was never able to achieve the same level of popular success as he had done with his role as Kuryakin. His best-known roles were in Sapphire and Steel (opposite Joanna Lumley), as the lead in a mid-1970s remake of The Invisible Man, and as Judas Iscariot in The Greatest Story Ever Told.

In the 1960s, McCallum recorded some albums for Capitol Records with producer David Axelrod, such as Music: A Bit More of Me (1966) and Music: It's Happening Now! (1967). The most well known of his pieces today is arguably The Edge, which was sampled by Dr. Dre as the intro and riff to the track The Next Episode. There is some controversy over what role McCallum actually played in these recordings, as he did not sing on the tracks (they are instrumentals), nor did he write them.

McCallum co-starred with Charles Bronson in The Great Escape. He introduced then-wife Jill Ireland to Bronson on the set and she later left him and married Bronson. As of December 2006, he is one of only four surviving stars of the film, the others being Richard Attenborough, James Garner and John Leyton.

McCallum appeared on stage in Australia when he appeared in the play Run For Your Wife , during 1987-1988 and the production toured the country. Other members of the cast in the production were Jack Smethurst, Eric Sykes and Katy Manning.

McCallum also guest starred in the television series seaQuest DSV as the law enforcement officer Frank Cobb of the fictional Broken Ridge of the Ausland Confederation, an underwater mining off the coast of Australia by the Great Barrier Reef during the series' first season.

In 1994, McCallum narrated the critically acclaimed documentaries Titanic: Death of a Dream and Titanic: The Legend Lives On for A&E Television Networks, the second Titanic-centric project he worked on. The first was the 1958 film A Night to Remember. A 1990s rock/rap group from Argentina named themselves Illya Kuryaki and the Valderramas in honor of The Man from U.N.C.L.E. character.

As of 2003, He is starring in the CBS television series NCIS as Dr. Donald "Ducky" Mallard. In an inside joke on that program, when Agent Gibbs is asked the question, "What did Ducky look like when he was younger?," Gibbs simply responds, "Illya Kuryakin."

According to the behind-the-scenes featurette on the 2006 DVD release of season 1, McCallum took it upon himself to become an expert in forensics in order to better play the role of Dr. "Ducky" Mallard, including appearing at medical examiner conventions. Bellisario says McCallum's knowledge of the subject became so vast that Bellisario (at the time of the interview) was seriously considering making him a technical advisor for the series.

He was married to the late actress Jill Ireland from 1957 to 1967. They had three sons: Paul, Jason, and Valentine. He has been married to Katherine Carpenter since 1967. They have a son, Peter, and a daughter, Sophie.

Bio from: imdb.com & wikipedia.org

Trivia

Fan club address: Lynda Mendoza, P.O. Box 313, Lansing, IL 60438-0313

Hit # 117 on the Billboard Singles Charts in 1966 with "Communication"

His hobbies include Golf and Computing.

His adoptive son, Jason McCallum Bronson, died of an accidental drug overdose in 1985.

Was stricken with rheumatic fever as a child.

Son, Val, is a respected guitar player and session musician; recording and performing with artists, Jonatha Brooke, Vonda Shepard and Sheryl Crow.