Ridley is the main antagonist of the Metroid series, and the nemesis of Samus Aran. Ridley is a high-ranking member of the Space Pirates, possibly even their leader, and had murdered Samus' parents when she was a child. Ridley goes through various forms of evolution prior to becoming a dragon-like creature, starting out as a creature dubbed "Little Birdie" before morphing into an adolescent form known as the "Mysterious Creature". Contrary to his appearance, Ridley is of high intelligence, showing knowledge in combat and giving orders to other creatures, as well as knowing when to retreat.
Ridley is brought back to life in Diet Cola Mountain by Bill Cipher and robotic version of Vanellope. When Ridley is reborn, he takes Vanellope to the top of the volcano, forcing the ponies to fight his minions, and solve puzzles.
When he is beaten, he will drop Vanellope, and scream in pain. He falls to his death in the hot Diet Cola, releasing a Chaos Emerald.
It is said that Ridley will be getting his own stand-alone movie that will dig deeper into his origins, who he once considered friends and enemies, and why he murdered the parents of Samus Aran.
Super Smash Bros. Fusion
Ridley appears as a Stage Boss on the Super Smash Bros. Fusion iteration of Super Smash Bros. 4's Pyrosphere stage. Ridley will occasionally fly over the stage, using his jackhammer tail to deal damage, roaring as he does. When he is at low health, Ridley will begin to pick up fighters and drag them across the wall, dealing massive damage. Unlike most stage bosses, Ridley is not always on the stage, as he occasionally flies back into one of the holes in the wall that appears in the background.
His inclusion as a stage boss has caused a negative reception from fans, due to him, once again, not being a playable character. The game's main director, Jake "TimeSoul", has specified that Metroid was set with two representatives, though added a third in Adam Malkovich.