Denis Clifford Quilley, OBE (26 December 1927 – 5 October 2003) was an English actor and singer. From a family with no theatrical connections, Quilley was determined from an early age to become an actor. He was taken on by the Birmingham Repertory Theatre in his teens, and after a break for compulsory military service he began a West End career in 1950, succeeding Richard Burton in The Lady's Not For Burning. In the 1950s he appeared in revue, musicals, operetta and on television as well as in classic and modern drama in the theatre.
During the 1960s Quilley established himself as a leading actor, making his first films and starring on Australian television. In the early 1970s he was a member of Laurence Olivier's National Theatre company. He joined the Royal Shakespeare Company in 1977 in the central role in Privates on Parade, which was later made into a feature film. His later parts in musicals included the title role in Sweeney Todd (1980) and Georges in La Cage aux Folles (1986).
In the 1990s Quilley returned to the National Theatre company, playing a wide range of parts, from Shakespearean comedy to Jacobean revenge tragedy, Victorian classics and his final role, a bibulous millionaire in the musical Anything Goes.