Eyedol was a common youth, who had his village ravaged by the evil warlord Gargos. Seeking revenge, he decided to become as powerful as him. However, he knew he wouldn't be able to defeat the warlord as a human so he challenged the gods to obtain ultimate power. He defeated the gods, and was granted the power he so desired, but the gods also cursed him, turning him into a two-headed Cyclops. Eyedol soon grew in power, creating his own army and becoming a warlord himself. He soon challenged Gargos, as the two armies clashed in a bloody combat that decimated many villages. Only the two warlords remained, so many sorcerers from the remaining villages united themselves and trapped the two warlords in the limbo, where they wouldn't ever be able to escape.
Two-thousand years into the future, the powerful company Ultratech, during one of their experiments, accidentally open the portal to the limbo, so Eyedol takes this opportunity to escape, landing inside their building. Severely weakened from his imprisonment, and now dealing with an unknown power (that of technology), Eyedol decides to go along with Ultratech's plans, being entered as the final combatant in their killer Instinct tournament. Eyedol defeated most of the combatants, but was ultimately defeated by Orchid. His defeat resulted in him losing control over his power, exploding in a huge blast that caused a temporal distortion, sending the entire Ultratech Building two-thousand years into the past, along with everyone inside it, and releasing Gargos in that era.
Eyedol is a two-headed, one-eyed monster who was trapped in a dimensional prison in the distant past. It is shown in Killer Instinct 2 that the person Eyedol was trapped in combat with was Gargos, the final boss of that game. Eyedol is the only character that does not have an icon in the character select screen, however in both the arcade and Super Nintendo versions he is a secret character that can be played as by selecting a specific character (Riptor in earlier arcade versions and Cinder in later arcade versions and in the Super NES version) and pressing a combination of buttons before a round begins. He is also the only character in the game with no special finishing moves, such as No Mercy moves, ultra combos, or humiliations that the other characters possess; however, he more than compensates for this lack of ability with a limited ability to heal.
Purely as a joke, if played to his ending, this ending would have a woman rush up and claim to be Eyedol's mother, and that his real name was Billy. This was a parody of Blanka's ending from Street Fighter 2. After hearing her story, however, Eyedol used his club to smash the woman into the ground, dismissing her claim, and, it seems likely, killing her.