Wolf of Fenric
From Tardis Wiki, the free Doctor Who reference
A Wolf of Fenric was one of many descendants of a Viking tainted with Fenric's genetic instructions to free it from its ancient prison.
Ace was a Wolf of Fenric. (TV: The Curse of Fenric) An alien named Halogi-Kari was the Wolf of Fenric who arranged for Ace to be dropped onto Iceworld. (PROSE: At Childhood's End)
