Donna Noble was pushed to her emotional limits in Turn Left when the fate of the entire universe rested solely in her hands. No pressure, then! After a fateful encounter with a time beetle, everybody's favourite temp from Chiswick found herself in a whole new world where she'd never met the Doctor, which was basically a sorry place for everyone. She was willing to give it all up, of course, in exchange for a new life of travelling the stars, and this tearjerking speech beautifully encapsulates just how much of an unsung hero she really was. All hail Donna Noble!