1. The DoctorDonna
At the risk of sounding dramatic, the DoctorDonna is probably the biggest and best plot twist in all of recorded history. ...Ok, maybe not. But it is pretty incredible. What makes the DoctorDonna so fantastic and surprising is the way the foreshadowing of Donna's vital connection to the Doctor and to the whole of time and space is woven with expert subtly throughout series 4. There are moments which hint at Donna's importance, and to her essential relationship with Ten. But when, at the crucial moment, the DoctorDonna appears to defeat the Daleks, the revelation is surprising, funny, and absolutely brilliant. The interaction between Doctor-Donna and the Donna-Doctor is also incredibly entertaining, as their banter is quick and impressive. It is one of the most satisfying resolutions to any Time Lord crisis.