[Crashpunk]

So I've heard a lot of rumours that Doctor at the end.

He is a in-between incarnation between the 8th and 9th or he could be the actual ninth Doctor making Eccleston the tenth. In other words, he's the doctor that fought in the Time War.

Personally, I don't know what to believe. The Doctor did something awful in any case, so maybe he's been keeping this incarnation a secret for a reason.