Devimon

Devimon is a Fallen Angel. He was once an Angemon, but soon the space of the Digital World became distorted, and he fell into the newly-formed Dark Area and became the fallen angel we see today. On his chest is embodied greatly a mark of evil, proof of his wickedness. He is a cunning old devil who takes no chances and refuses to play mindless games with enemies as powerful as he is. He is wicked and ferocious, but he is very loyal to his master with whom has concluded a pact. It is said that should you be influenced into staring at his crimson eyes, he will control your mind. IceDevimon is his ice counterpart. Devimon was known as Darkmon in the Tamagotchi Digimon virtual pets and is also known as the Dark Messenger. He is one of the few villains to have his own image song. It is entitled "Dark Wing" and appropriately ends in a chilling, villainous laugh. (source: Wikipedia)

Devimon is the first main villain in both Digimon Adventure (1999) and Digimon Adventure: (2020).