2001: A Space Odyssey (soundtrack) used is Ligeti's "Lux Aeterna" and an electronically altered form of his "Aventures", the last of which was so used without Ligeti's permission and is not listed in the film's credits. Since the film, "Also sprach Zarathustra" has been used in many other contexts. It was used by the BBC and by CTV in Canada as the introductory theme music for their television coverage of the Apollo space missions, as well as stage entrance music for multiple acts including Elvis Presley late in his career. Jazz and rock variants of the theme have also been composed, the most well known
2001: A Space Odyssey (soundtrack) stages of production, Kubrick had actually commissioned a from Hollywood composer Alex North, who had written the score for "Spartacus" and also worked on "Dr. Strangelove". However, during postproduction, Kubrick chose to abandon North's music in favor of the now-familiar classical pieces he had earlier chosen as "guide pieces" for the soundtrack. North did not know of the abandonment of the score until after he saw the film's premiere screening. Also engaged to score the film was composer Frank Cordell. Cordell stated in interviews that the score would primarily consist of arrangements of Gustav Mahler works. This score remains unreleased.