First Doctor was played by William Hartnell from 1963-1966. He was initially a very cantankerous old man, much more interested in saving himself than the universe. He also thought himself above humanity until he was about to kill a caveman in cold blood. He was stopped by Ian Chesterton, a schoolteacher of his granddaughter Susan's whom he had kidnapped along with fellow teacher Barbara Wright because they were investigating where Susan came from and happened upon the TARDIS. Without Ian's quick thinking, the Doctor wouldn't have become a much more compassionate figure. He regenerated for the first time after he had pushed his first body to the limit following his first battle with the Cybermen.