Bred by Evil to slay
what could be slain in no other way.
Bred to guard that which went astray
and within the great bowels lay.
Slayer and slain all at one time
his death brought all the light to shine.
Carcharoth
Carcharoth was bred from the foul breed of Draugluin, the first Werewolf, and fed with elvish and mannish flesh by Morgoth himself. (Source: The Silmarillion)
Tolkien Gateway: Carcharoth