1st Doctor

"One day, I shall come back. Yes, I shall come back. Until then, there must be no regrets, no tears, no anxieties. Just go forward in all your beliefs and prove to me that I am not mistaken in mine. Goodbye Susan. Goodbye my dear."

- The First Doctor to his granddaughter Susan (spoilers: he never came back)

 - Previous: None - Current: 1st Doctor - Next: 2nd Doctor -  The First Doctor is the first incarnation of the Doctor, and is thus the youngest (despite his appearance).

The Doctor traveled on crazy and fun adventures with his granddaughter Susan. Eventually, he abandoned her, lied and told her he would come back (he never came back) then chose some spunky new companions to travel with.

This Doctor was probably the biggest jerk out of them all, and that's keeping the swears Christian-friendly.

Eventually the Doctor got hurt really bad, and he thought changing his face would be a good idea. So he turned into the second doctor and decided to be a little bit nicer from then on.

Until he turned into the Valeyard. But we don't talk about him (is he even canon to Doctor Who, really?).