Dagon (Ben 10)

Diagon is an interdimensional demonic entity.

Biology
In his true form, Diagon appears as a giant green octopus-like creature. In the legend of Saint George and the Dragon, Diagon took the form of a black scaled western dragon with a green belly and wings. When he fought against Ultimate Way Big, Diagon took on a form similar to his true form but with a more serpentine-looking body.

Appearances

 * Ben 10: Ultimate Alien, s03e10, "A Knight To Remember" (2011)