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.
Metroid
"Metroid", "", "Super Metroid", "Metroid Fusion", and "" were all developed by Nintendo's internal R&D1 division. The games which have been developed by separate teams are "Metroid Prime", "", "" and "Prime 4" (Retro Studios), "Metroid Prime Hunters" (Nintendo Software Technology Corporation), "Metroid Prime Pinball" (Fuse Games), and "" (Project M). The central figures in the production and development of the "Metroid" series are Satoru Okada, who directed "Metroid" and created the series; Yoshio Sakamoto, who acted as a character designer for the first game and has directed or supervised the development of most of the subsequent games; Gunpei Yokoi, who headed the R&D1 division and produced the first two games; Makoto Kano, who wrote the scenario for "Metroid", co-designed the second game, and produced the third; and Hiroji Kiyotake, who designed characters for the original game. "Mario" and "The Legend of Zelda" creator Shigeru Miyamoto was involved with the "Prime" trilogy, having been the one that suggested Retro to work with the franchise.