A cache based on the titular character from the long-running British sci-fi series Doctor Who. However, as the titular character (a time-traveling alien Time Lord known as the Doctor) has multiple incaranations (called regenerations on the show), this cache will focus on the ninth incaranation, the War Doctor. Doctor Who is actually 2 separate shows: the original run of the show from 1963 to 1989, consisting of 26 seasons have seven actors portraying the Doctor (the First through Seventh Doctors). The modern show consists of 11 series (and counting), with five actors or actresses portraying the Doctor (the Ninth through Thirteenth Doctors). The Eighth Doctor appeared in a TV movie in 1996, between the 2 shows.
On the 50th anniversary of the show, it was revealed there was one more Doctor between the Eighth and Ninth Doctors: the War Doctor, portrayed by John Hurt. The War Doctor's appearances are limited to only 3 television stories, partially because of the nature of the guest appearance for the anniversary, and partially due to the passing of John Hurt. The character has an ongoing presence in non-television stories, such as audio dramas (which Hurt recorded after the 50th anniversary) novels, and comics.
In the show, a great Time War raged between the Time Lords and the Daleks, threatening all of reality. The Eighth Doctor did not get involved in the fighting until a fatal crash on Karn. He was given a brief return to life and opted to regenerate into a warrior to help save all reality. The new Doctor proceeded to fight on the front lines of the Time War across all of time and space. It's unclear how long the Time War takes from the Doctor's perspective, but by its end he has aged significantly. At the end of the war, the Doctor struggled with the choice to use a doomsday device called the Moment to kill both the Daleks and Time Lords, the price to save the rest of reality.
As he considered the choice, he encountered his future incaranations, the Tenth and Eleventh Doctors. After adventuring with them briefly, he decided to use the Moment to save reality, only to be stopped by his future selves in an attempt to find an alternative solution. Teaming up with twelve other incaranations of himself, the Doctor saved the Time Lords (on their home planet of Gallifrey), and ended the Time War. Bidding his future selves farewell, he regenerated into the Ninth Doctor (due to old age of his current form). Due to the nature of time travel and meeting his future selves, the Doctor did not remember saving Gallifrey until he experienced the events the third time (as the Eleventh Doctor), and the Ninth Doctor believed he destroyed Gallifrey and lived with that guilt for several more incarnations.