4. The End Of The World
"Everything has its time and everything dies."
The End of the World was the first "proper" episode of nu-Who, with Rose being dominated by the requirement to introduce a new companion. So The End of the World was the first time we saw what nu-Who was going to be like and how the Doctor/companion interaction was going to work. It also gave us the first proper hints at the results of the Time War with the awe that Jabe of the Forest of Cheem holds him in. The characters in this episode would be referenced on several occasions in later seasons, with Cassandra and the Face of Boe both reappearing during the David Tennant era. But it is when Eccleston's Doctor is reminded of the Time War that we saw a sorrow and darkness in the Doctor for the first time. At the time of the first airing, this simply hadn't been seen before and so it showed a great deal more of a character that became better rounded after time. It was the first time that the Doctor has been seen to cry. The End of the World set the characterisation of the Doctor during the Eccleston era in motion. In fact, it is the basis for all the nu-Who characterisation of the Doctor during the various eras. This was the starting point, and almost a statement to viewers about who this character was. Whilst Rose explained Rose Tyler, The End of the World said exactly who the Doctor was.