Ridley (Metroid)
Often considered one of the most memorable Nintendo villains, Ridley has been a mainstay of the series, having appeared (through various incarnations) in almost every "Metroid" game to date (all but "", "Metroid Prime Hunters" and ""). He has also appeared in the "Super Smash Bros." series, however, he had not been made a playable character until "Super Smash Bros. Ultimate" in 2018, making it also the first game overall to have Ridley as a playable character.
List of Mega Man characters
Another note is that his name is Cain, the biblical man who betrayed and killed his brother, Abel. In a similar fashion, Dr. Cain unintentionally betrayed humanity to doom and destruction for generations to come in his creation of Reploids. The city that he lives in, and the Main maverick Hunter base was stationed in Maverick Hunter X, also, was aptly named, "Abel City"