The Cannibal was a wild dragon that lived on Dragonstone during the Dance of the Dragons. He would feast on dead or newborn dragons and their eggs. The smallfolk of Dragonstone named it for a self-evident reason. He was one of three completely wild dragons dwelling on Dragonstone, the others being Sheepstealer and Grey Ghost.
The Cannibal was black as coal. He was the largest and oldest of the wild dragons. He was known to descend upon the hatcheries of Dragonstone to gorge himself on newborn hatchlings and eggs. The Cannibal was known to attack smaller dragons. He laired at the back of Dragonmont. Prior to the Dance of the Dragons a dozen would-be dragon tamers had made attempts to ride him and his lair was littered with their bones.
The Dance of the Dragons Edit
When Prince Jacaerys Velaryon called for dragonriders during the Dance of the Dragons none of the dragonseeds were fool enough to disturb the Cannibal due to his reputation - and any who were did not return to tell the tale.
When Silver Denys, a man who claimed to be a descendent of King Maegor I Targaryen, tried to master Sheepstealer the dragon tore off his arm. As his sons struggled to staunch his wound the Cannibal descended on them, drove off Sheepstealer and devoured Silver Denys and his sons.
When the carcass of the Grey Ghost was discovered at the the Dragonmont's base Ser Robert Quince was quick to name the Cannibal as the killer (in fact it was Sunfyre). The fisherfolk began to worry that the dragon would turn upon them and urged Ser Robert to have the Cannibal dispatched but he refused, reasoning that if they left the dragon alone he would not bother them.
Archmaester Gyldayn in his history of the civil war makes no mention of the Cannibal perishing during the Dance of the Dragons so presumably he survived.