Ron Grainer
From Tardis Wiki, the free Doctor Who reference
Ron Grainer (11 August 1922-21 February 1981) was an Australian composer who worked for the BBC in 1963. Most notably he wrote the Doctor Who theme/score, which Delia Derbyshire went on to perform. He has been credited in every Doctor Who episode in the original and new series except for the 1996 television movie.
He also wrote the theme music for other noted series, including Steptoe and Son, Man in a Suitcase and The Prisoner. His film credits include The Omega Man.
He is still constantly credited for "original theme" in Doctor Who after his death.
