The Doctor

The Doctor was the last Time Lord from the planet Gallifrey after destroying his home to end the Time War between the Time Lords (his people) and their enemies, the Daleks (aliens from the planet Skaro who are best described as deadly racist hate stuffed into a metal casing). The Doctor travels through time and space in his TARDIS which is shaped like a London Police Box from the 1960s which is bigger on the inside than the outside and often very unreliable when it comes to directions. The Doctor is usually thought of as a hero, and uses his great intellect to save planets and get himself out of sticky situations. He has the power of regeneration to save him from death, although at the end of The First Adventure the Doctor was on his 12th and penultimate life.

FoA
Since joining the Fellowship of Awesomeness, the Doctor has mainly been in charge of transporting the Fellowship with the aid of his TARDIS. However, he has also used his knowledge of the universe to help the Fellowship destroy the Ring, including, with the aid of Sherlock Holmes, discovering that the Fellowship was stuck in a dream world and how to escape that world.

Powers

 * Total cellular Regeneration (although he can only do this one more time before final death)
 * Extremely intelligent with a great knowledge of almost everything in the universe (well, his universe at least)
 * Time/space machine which can materialise anywhere (although not always where one intended it to land)

For more information on the original character, see Tardis:the Doctor.