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
The Maverick Hunters (Irregular Hunters in Japan) are a group of Reploids who protect humans and other Reploids from Mavericks and the heroes of the "Mega Man X" series, and the protagonists of each game are prominent Maverick Hunters. When they are introduced in "Mega Man X", they have already existed for quite a while, having been previously founded by Dr. Cain (who has since retired). From "Mega Man X" on, they battle Sigma and the other Mavericks.