Doctor Who (UK) (1963)

The Second Doctor is very different from his blustery old self. So different, indeed, that, initially, his companions Ben and Polly could not believe that it was the same man. Indeed, the Doctor, in his post-regeneration state, referred to his first self as an entirely different person. It seems that the only things he shares with his predecessor are his insatiable curiosity, wide range of knowledge, and general morality.

Whereas the first Doctor was content to explore the universe, the second believes that he has not just a right, but a duty to interfere in the cause of good. He takes pleasure in interfering. Even when his own people tried him for interference, he was unrepentant for the marks he has left in history. In fact, he even berated the Time Lords for their refusal to interfere.