8. Wilfred Mott
He might not be one of the first characters that springs to mind when you think of the Doctor's companions but Wilfred Mott, the granddad of other companion Donna Noble, was a regular character in Series 4 before being promoted to companion for David Tennant's swanswong The End of Time. His name's even in the opening credits. And only Doctors and companions get that privilege (let's just ignore the fact that John Simm's Master also weirdly gets the honour in that episode). Apart from his unconscious granddaughter, Wilf was the last human remaining on Earth when the Master converted the human race into himself and stood by the Doctor's side when the Time Lord began to break under the threat of his impending doom. In the end, Wilf himself was inadvertently the cause of the Doctor's death when he saved Wilf from a radiation chamber. It happens. A kind, funny and very noble (geddit?) old man, he may have only been a companion for one adventure but Wilf thoroughly deserves his place on this list. Also, he's played by the loveable Bernard Cribbins. Do you really need any other reason?