Doctor Who is an alien who travels through time and space on his spaceship, the TARDIS (Time And Relative Dimensions In Space). Get Doctor Who coloring pages here.
The Tardis looks like a British police phone booth from the outside, but it is much larger inside. The Doctor takes on strange space monsters and other alien baddies during his adventures.
One of the Doctor’s valuable features is that he can renew his body when injured. This is why he looks different each time in the television series.