Desmond Llewelyn was lucky, because actor Peter Burton, who had played Q in the first James Bond film, Dr. No (1962), was unavailable for the second. The windfall would last 17 films, until 1999's The World Is Not Enough.
At first, Llewelyn was all business - in fact when Bond questions "Q" on the very idea of an ejector seat in the "Goldfinger" Aston Martin, Llewelyn's perfectly dry response was "I never joke about my work, 007."
With Bernard Lee's "M", and Lois Maxwell's Moneypenny, he became a staple of the Bond series - with his "gadgets" becoming an audience favorite, and his frequently annoyed repartee with Bond being a comic highlight. In You Only Live Twice (1967), he brings the fabulous Little Nellie autogyro to Japan. For some reason, his character wasn't written into Live and Let Die (1973), but he got his biggest part in the Timothy Dalton picture, Licence to Kill (1989), becoming a trusted agent comrade in Bond's battle against the formidable drug runner, Franz Sanchez (Robert Davi). Tall, well-dressed, and possessing an impeccable voice, Llewelyn was one of the most beloved characters in the series.
Most sadly, Desmond was killed in a traffic accident in December 1999, returning home from a book signing event, a tragic loss. His traditional briefing with Bond is carried on today by Ben Whishaw, a very youthful and geeky Q.
James Bond (Timothy Dalton) gets kitted out for his mission by Q (Desmond Llewelyn) in The Living Daylights: