Werewolves

"...now was he Morgoth's mightiest lord, Master of Wolves, whose shivering howl for ever echoed in the hills..."

- On Sauron/Thû and his werewolves Werewolves occasionally called Wolves are servants of the dark lords Morgoth and Sauron, the main antagonists of Beren and Lúthien.

Beren and Lúthien (Silmarilion)
"Wolves should come and slow devour them one by one..."

- On Beren and his companion's fate at the hands of the Wolves of Sauron/Thû Werewolves serve Sauron the dark lord in his fortress of Tol-In Gaurhoth. They capture Beren, Fingon the Elf King of Nargothrond and their companions and bring them before their master, who recognizes them as not being his Orcs and has them imprisoned in the dungeons, where the Wolves of Sauron go to devour them each.

When Lúthien and Huan arrive to rescue Beren, Sauron comes to desire the Elf-maiden for himself and sends his werewolves to bring her back to him. The creatures and their Sire Draugluin are slain by the Hound of Valinor and the dark lord himself is defeated. The Servant of Morgoth yields the keys of his tower and flees.