Theme

The term of theme or theme song can refer to the signature music of a series or stand-alone work, often playing over the opening credits. In many cases, the composer of the original theme song was not the same person as the composer of the incidental music, meaning the composer of the theme would get a separate credit from the incidental soundtrack composer in every episode using the theme.

Television themes
The Doctor Who theme was composed by Ron Grainer, with the original 1963 arrangement being the work of Delia Derbyshire.

The Torchwood theme was composed by Murray Gold and Ben Foster.

Home video themes
The P.R.O.B.E. theme was composed by Mark Ayres. It was used in all five feature-length direct-to-video P.R.O.B.E. films and a shortened version was used in the opening credits of the shorter P.R.O.B.E. Case Files.

Theatrical themes
Dr. Who and the Daleks and Daleks' Invasion Earth 2150 A.D. both had unique themes not used anywhere else, referred to as the "Main Titles" on the official soundtracks. The former was composed by Malcolm Lockyer and the latter by Bill McGuffie, in both cases also the composers of the movie's instrumental soundtrack.

Audio themes
The theme song used in The Faction Paradox Protocols was composed by Nigel Fairs. A more upbeat version was used in the first two releases, before being replaced by a different arrangement with a more somber, dark-fantasy aesthetic from In the Year of the Cat onwards; Fairs explained that he had misjudged the intended tone of the series with the first version, expecting a more quirky, comedic series in the style of Douglas Adams and composing accordingly. (REF: Downtime – The Lost Years of Doctor Who) When the Faction Paradox audio rights we transferred to Magic Bullet Productions, a different theme was composed by Alistair Lock.