The Legendary Graug is a Graug in Middle-earth: Shadow of Mordor. The Legendary Graug killed Gorvin, Torvin's brother, who now hunts the creature in the Sea of Núrnen. After a decade of tracking the Graug, Torvin kills The Legendary Graug with the help of Talion. The Legendary Graug boss fight starts after one of Celebrimbor's flashback. During the fight it will eat Ghûls to regain its health; it must be injured it 3-4 times before it dies.
The legends tell of a Graug towering over all others, a thirty-foot tall monstrosity whose shadow covers half of Mordor and can grasp an entire forest in its fist. Perhaps, as those who speak of it have suggested, this is no monster at all but a demon of stone and fire, a Balrog, given flesh.
If such a monster exists it would be a magnificent prize for the Uruk Warchiefs gathering in Mordor. The Dark Lord knows of its existence and plans to harness it for his armies. A Graug of that size could turn the tide of any battle.