Fenrir Greyback

"Fenrir Greyback is, perhaps, the most savage werewolf alive today. He regards it as his mission in life to bite and to conta­minate as many people as possible; he wants to create enough were­wolves to overcome the wizards. Voldemort has promised him prey in return for his services. Greyback specialises in children... Bite them young, he says, and raise them away from their parents, raise them to hate normal wizards."

- Remus Lupin

Most are disgusted or ashamed when afflicted with the disease that causes one to become a bloodthirsty werewolf; Fenris Greyback, meanwhile, lives through them with savage glee. Once Greyback became afflicted with lycanthropy, he embraced his animlastic nature. Seeking to overwhelm the Wizarding World, Greyback is reknown for his savagry and his particular love of children. Believing that attacking them young will corrupt them further, Greyback is attempting to overrun the wizard population by creating an army of powerful werewolves to serve him.

During the 1990's and the Second Wizarding War, Fenris Greyback owed his allegiance to Lord Voldemort under the promise of several wizards to satisfy both his plans for domination and his own cannibalistic hunger. Despite the disgust many Death Eaters found for Greyback and his pack, many acknowledged his usefulness as a hunter and assassin. Greyback served Voldemort faithfully, battling against Harry Potter and then burning the house of his best friend's family to the ground alongside Bellatrix Lestrange. The two servants of Voldemort then captured Harry and his companions, but were unable to maintain hold of them.

As Voldemort's army prepared to lay siege to Hogwarts Castle, Fenris led his pack of werewolves against the students and faculty of Hogwarts, as well as the Order of the Phoenix. Fenris and his pack managed to murder several students, ranging from first year children to fully grown seventh years, until Fenris was finally defeated by Ron Weasley and Neville Longbottem after killing their friend Lavender Brown.