A very rare, young, white Ceratopsian Digimon that was recently discovered. Gammamon's evolution is said to be linked to a "digital signal that came from extragalactic space".

The two hard horns that grow from its brow are weapons that are useful for offense and defense. It is also capable of levitating, and flying for a short period with the tiny wings on its back. Gammamon rarely shows its emotions, but it seems that once you reach out to it, it will gradually grow attached to you.

Gammamon came to Hiro through his father, Hokuto. Brimming with curiosity, it has a habit of trying to bite everything. Despite being mischievous, it obediently listens to what Hiro and the others say. Its favorite food is chocolate, going as far as calling it "the best".

Gammamon can evolve into BetelGammamon (Champion), KausGammamon (Champion), WezenGammamon (Champion), Canoweissmon (Ultimate) and Siriusmon (Mega).

As its original attribute is "virus", Gammamon also can evolve to Gulus Gammamon (Champion), Regulusmon (Ultimate) and Arcturusmon (Mega). When in harmony, Siriusmon and Arcturusmon together can evolve into Proximamon (Mega).

In Digimon Dreamers, Gammamon and Amanokawa Hiro make a small cameo, passing by Kodou Ritsu, Pulsemon, Bokomon and Patamon.