Digimon Adventure:

Season 1, Episode 65

Episode Title: The Great Catastrophe, Negamon

Air Date: 2021-09-12

Overview:

The DigiDestined looked, and behold a dark octopus with an unique yellow eye. The true form of the Great Catastrophe is revealed through Algomon's words: and his name was Negamon, and the end of all things followed with him.