Adrian Gecko, known in the Japanese version as Amon Garam is a new student hailing from East Academy who enters Duel Academy in the third year. Reserved and secretive, Adrian is a neutral character whose actions seem to only serve the Gecko Family and himself. However, after acquiring the spirit of "Exodia the Forbidden One" in the third alternate dimension, he intends to rule it and acts as a major antagonist towards Jaden and company.

His given name in the Japanese version is derived from an alternate spelling of the name of an Egyptian air deity, Amun.

In the Japanese version, the older Adrian is voiced by Saichouya, while in flashbacks, the younger Adrian is voiced by Saori Terai. In the English dub, Xaivor Willis takes the part of his voice acting.