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.
Murderworld!
"Murderworld!" is the third module produced for use with the "Marvel Super Heroes" game. Despite Arcade being the headline villain, the module does not feature the X-Men, but rather the Fantastic Four. Many of the group's more regular opponents also make an appearance, including Victor von Doom.