Doctor Who centres on a rogue Time Lord from the planet Gallifrey, referred to only as The Doctor. He’s known to have escaped from there in a stolen TARDIS (Time And Relative Dimension In Space), which is essentially a transportation device designed for travel through time and space, and it’s much bigger on the inside than it is on the outside. Though it was originally designed to have a chameleon-like quality – enabling it to take on the appearance of objects around it in order to ‘blend in’ – it has long-since suffered a malfunction and is stuck with the appearance of an old, British police box. It changes on the inside, though, with each new Doctor.
As a Time Lord, The Doctor is centuries old and has the ability to regenerate when necessary. This process provides a new body and a new personality, while memories and knowledge are largely retained. In terms of the time-travel based narrative, this means that different incarnations of The Doctor can run into each other at pivotal points. The Doctor has an intellect that is far beyond genius-level, and uses this ingenuity – along with a trusty sonic screwdriver – to help beleaguered creatures across the universe. Though The Doctor assists a broad range of beings, a particular fascination with the planet Earth means that humanity receives special attention.
During Earthly escapades, The Doctor has often collaborated with the military taskforce UNIT (originally known as the United Nations Intelligence Taskforce, but renamed the Unified Intelligence Taskforce from 2005 onwards). This has led to adventure and drama galore, as The Doctor and his associates fight to keep humanity safe from alien threat, while the majority of the population live out their lives oblivious to the precarious nature of galactic peace.