Much like the richness of the Melody Pond theme above, the song of Gallifrey has a history and power to it, entrenched with the Time Lords. Ebbing and flowing, this theme has been used across the series to show the strength and power, the danger and eventual return of the Doctor’s home planet. Here it is being used to remember the past of the Doctor, with the more violent ending becoming very symbolic of the threat that Gallifrey poses; a threat that the Doctor would have to face much later.
Title Sequence: Multiple
Whilst that is the end of my list, it seemed to be inappropriate not to mention the theme that is synonymous with the series. The opening credits of Doctor Who has evolved over time and here is a video demonstrating that. However, there is always a similarity between them, always a freshness and always a quality score. Indeed, the series may just have some of the best themes in all of sci-fi.
George Chrysostomou