Gelios (ゲリュオス, Geryuosu) and John Owen (ジョン・オーエン, Jon Ōen) or John Ouen, are an ancient Mamodo team who confronted Zatch Bell and Kiyo Takamine and Tia and Megumi Ooumi, along with Alm. Their spells involve Armor. John Owen is a baseball player, which mind is brainwashed for Zofis. John's Japanese voice is provided by Keijin Okuda; English voice is provided for Kyle Hebert.
Gelios is at the water reservatory, along with Alm, protecting it from any intruder, and then they meet Kanchomé, who distracts them into a trap. After this, Ganz appears and he's taken for Kanchomé and Folgore (after Ponygon follow them). However, Alm and Gelios wake up and start attacking Zatch, Kiyo, Tia and Megumi. After using Akur on them, Kiyo makes a plan to escape from Gelios' attack. The two ancient mamodo then follow they into a more lower arena. There Zatch starts using a strategy to burn their books: Don't hit the bookkeepers. Later, they use their strongest spells: Egdoris Neshiruga, Bao Zakeruga, Gigano Dioderuk and Ma Seshield. While those attacks cancel each other, Megumi gets Alm and Gelios' books. Seeing that there's no chance of winning, Alm tells to them everything that he knows, and fades along with Gelios.
In the manga Gelios's spirit is seen assisting Zatch along with the other Mamodo's in his final attack against Clear Note, After Zatch became king he was revived along with the other Mamodos and is shown to be in the same grade as Laila, Pamoon, Hyde, Reycom, Pokkerio, and Paramakion.
Gelios is a snake-like mamodo whose face is reminiscent of a court jester. He posseses only one water spell (Akur) in the anime, and in the manga he has only the three other spells. John Owen is a man that's probally a baseball player, and he's a fan of Folgore, along with Mamiko (Alm's partner).