The Doctor.
Any fan has a list of characteristics that come to mind when they think of the central character in the popular British television show. He cares about the people and species that he comes in contact with and does everything within his power to save them from threats they may be facing. Everything he does is with good intentions and he can't seem to bring himself to kill anything or anyone, even if they have proven to be his enemy.
The ninth incarnation of the Doctor, portrayed by Christopher Eccelston, just came out of the Time War, where he was responsible for the death of his entire race. Because of this, he is very bitter and doesn't always seem to care as much as he should about the people around him. However, he couldn't even bring himself to kill the Daleks, a race he has been fighting since the very beginning. Why? Because above everything, the Doctor values life.
But recently, these characteristics seem to be changing, and definitely not for the better. The Doctor is acting much more selfish and often regretting his actions to save people. He doesn't even seem to care if he dies.
I noticed this especially in "Under the Lake" and "Before the Flood." Though my opinion on the season and the twelfth Doctor had slightly improved by "Before the Flood", I still didn't necessarily like him. In this story arc, the Doctor and Clara are trapped underwater along with a group of other people. His main focus is to save Clara. The Doctor has no desire to save himself, or the other people with him. He risks his own life and the lives of the others in order to save Clara.
This mentality continues on through the entire season, even until the end, when the Doctor risks tearing apart the entirety of time and space just to save Clara from dying.
Yes, the Doctor's personality and tastes in different things change every time he regenerates, but his core values and beliefs always stay the same — this is what makes the Doctor who he is. The Doctor saves people.