You likely recognize him from his long-standing role on the crime-drama, NCIS as Dr. Mallard or "Ducky."
But, don't be fooled by his role as the distinguished doctor, in fact Mr. McCallum has a few surprising acting facts you might not have known about.
As we celebrate his 83rd birthday and 65 years in the business, see how much David trivia you knew!
Before he was distinguished Ducky, he was a sex symbol.
In the American spy series that ran from 1964-1968, The Man From U.N.C.L.E, McCallum played the mysterious Russian spy, Illya Kuryakin.
His character was originally supposed to be a minor role, but he did such a good job, and drew in such a massive following of female fans, that he was written in with co-star status.
He received more fan mail than any other actor in Metro-Goldwyn-Mayer's history.
His fan base was so huge, they followed him around in a Beatles-like frenzy and swamped him with love letters. He received more fan mail than Elvis Presley and Clark Gable!
They called him "The Blond Beatle" and "The Fifth Beatle"
He sure did know how to work those blue eyes! Fans loved him so much, a hit song was even written about his character. It was recorded by Alma Cogan and was a Pirate Radio hit in 1966.
He recorded four Albums in the 60's and his music is being sampled by rap artists today.
While studying for his role as Ducky, he attended Medical Examiner conventions.
He became so knowledgeable, that at the time of his audition, producer and screen writer, Donald P. Bellisario considered making him a technical adviser to the show!
Happy Birthday, David!