Balgrog

Balgrogs are an extinct species of Discworld fauna once native to S'belinde. They were very large animals with an extremely resilient skin for which they were hunted; both waterproof and strong it was prized as material for boots, coats, tents and of course Balrugs. The Smith family were known to posses a Balrug.

Balgrogs are first mentioned in Moving Pictures where a Troll is painted green and has a pair of wings attached to its back in order to represent the creature.

Later in The Compleat Discworld Atlas more information on the creature is revealed but they are named as 'Balrogs' instead of Balgrogs. This is likely a mistake as it replaces the Discworld monsters name with the name of the creature that it supposed to be parodying.