Dioskilos is two-headed dog and is related to the Underworld dog Cerberus. He appeared in the 1981 film "Clash of the Titans".
Dioskilos protected the Temple of the evil Gorgon Medusa and attacked any intruders who entered the temple. He ambushed Perseus and killed a member of his honor guard. Before Dioskilos could further attack Perseus who lost his sword to a nearby venomous snake in the ruins' rubble, he was engaged by two more guards for a time thereafter. Dioskilos was eventually slain by Perseus after recovering his sword, thus rescuing his remaining guards.
Dioskilos was the guardian of the evil gorgon Medusa who watched over the ancient ruins that rest in the Center of the Isle of the Dead. He was the size of an abnormally large dog, standing knee-high. Dioskilos had the unique ability to withstand several attacks from mortal weapons. His two heads could act independently and fight multiple enemies at once. He possessed a degree of agility as he could leap from ledges as well as off level ground. Dioskilos could still survive even after one of its heads is killed. Both heads required slaying for Dioskilos to be completely dead.
Dioskilos' real name was Orthrus and he was the Son of Echidna and Typhon.