Omegamon (called Omnimon in the US) is a Mega-level Digimon that's shown up across multiple series in the franchise. Fans recognize him as one of the strongest Digimon around, with a distinctive design: his two hands are actually shaped like the heads of Wargreymon and Metalgarurumon, and he's covered in a massive white cloak.
His appearances vary depending on which show or movie you're watching. In *Digimon Adventure - Bokura no War Game*, he DNA-evolves from Wargreymon and Metalgarurumon during the story's climax—a pretty iconic moment for the franchise. He pops up briefly in *Digimon Tamers: The Adventurers Battle*, then takes on a more prominent role in *Digimon Savers* as the leader of the Royal Knights, serving under Yggdrasil, the god of the Digital World. The 3D-CG film *Digital Monsters X-Evolution* makes him a main character again, still acting as one of Yggdrasil's enforcer knights.
*Digimon Xros Wars* has him helping Taiki by giving him the XrosLoader and getting him back to the Digital World. Over in the *Digimon D-Cyber* manga, he's positioned as one of the Three Holy Knights (along with Dukemon and Magnamon), specifically the Knight of Power, and they're collectively responsible for maintaining peace across the Digital World.
Content compiled by AnimeList.moe from publicly available sources.
