Doomsday is the main overarching antagonist of the Miraculous Red series, believed to be the rumored missing father of the Eberusu Family. He is responsible for activating the Golden Knight Miraculous and uses it for his evil ways of obtaining the Red and Rainbow Miraculous in order to reset the world into his own "perfect" utopia. To do so, he has two separate powers, one called Golden Destruction, which basically is the complete opposite of Red Noir's Red Aura, and Akumatization where he summons a butterfly, uses his Miraculous Magic to turn it gold and sends it out to those who show negative emotions. These akumas can akumatize anyone into his own supervillains.

Doomsday's personality is a strange mix of courage, sadism, and malevolency, and as well as high intellectual capacity. This gives him off as one of the most dangerous villains in the series. He's also very cunning using giving his akumatized villains information provided to take the Red and Rainbow Miraculous to complete his world dominance. He is also exceedingly power-hungry and greedy, aiming to stop at nothing to defeat the heroes once and for all. He also will punish other akumatized villains if they do not do what he says by stripping them away from their power and controlling their every movement.

However, he can make it up to his akumatized villains by offering constructive criticism and encouragement to go in at any hero that attempts to stop them in the process, especially if Red Noir is present in the battle to take their akuma away from them.