Originally Posted by
dps
First, do you have a source for that assertion? True, there haven't been any instance of purely mundane threats since 1982, and before that none since very early in the 2nd Doctor's run, but I'm not aware that it's a set policy by the BBC.
Second, technically neither Silurians nor gangers are extraterrestrial. And maybe not the Silence, either, but that's not quite clear. And that's just limiting it to threats faced by the 11th Doctor. But if your assertion is true, I guess all 3 and other, earlier examples, might be close enough.