He resumed his acting career following the war, making his first post-war television appearance in a 1946 adaptation of As You Like It. Throughout the Fifties he appeared frequently on television, including playing Sydney Carton in an adaptation of A Tale of Two Cities, appearing as a regular on the TV series My Wife Jacqueline, and guest starring on The Adventures of Robin Hood. He had bit parts in such films as Knights of the Round Table (1953), A Night to Remember (1958), and Sword of Sherwood Forest (1960).
It was in the Sixties that he would first play his most famous role, that of Q in the James Bond movies. He first played the quartermaster and armourer in From Russia with Love (1963). He would go onto play Q in 17 James Bond films (every film after From Russia with Love and up to The World Is Not Enough except Live and Let Die). Ultimately Desmond Llewelyn appeared in more Bond movies than any other actor in the history of the franchise. Even while appearing as Q, Mr Llewelyn found time to appear in other projects. On television he played the Colonel on Follyfoot. He also appeared in such films as The Pirates of Blood River (1962), Chitty Chitty Bang Bang (1968), The Golden Lady (1979), and Merlin (1993).
In honour of Desmond Llewelyn's 100th birthday, here is a collection of clips of Mr Llewelyn as Q, including the tribute Eon Production created for him upon his untimely death in 1999, "Now Pay Attention 007: A Tribute to Actor Desmond Llewelyn".