Doctor Who: Every Prophecy In The Show - Explained
9. The Prophecy Of The Bad Wolf
We see and hear the words "Bad Wolf" on many occasions throughout the first series of NuWho, whether they're graffitied onto the side of the TARDIS, or given as the code name for a descending helicopter, as seen in Dalek.
Missable easter eggs aside though, there's one particular scene in which the phrase is used in a clear prophetic manner.
In The Unquiet Dead, the Ninth Doctor and Rose Tyler meet a lady called Gwyneth, who possesses psychic abilities. During a conversation with Rose, Gwyneth reads her mind, getting hints of a mysterious "darkness" and a sinister "big bad wolf".
"You've flown so far. Further than anyone. The things you've seen. The darkness... the big bad wolf."
This doesn't make much sense at this early stage in the series, but in the finale, the Bad Wolf is revealed in all its glory: it's Rose herself, wielding superhuman powers after staring into the heart of the TARDIS. With these powers, she comes to the Doctor's aid, vanquishing the Daleks and resurrecting Captain Jack.
The Bad Wolf then scatters those iconic words throughout space and time, which explains why they appear throughout the series. We can also assume that Gwyneth's psychic powers allowed her to sense this, which led to her delivering that prophecy.