This article is about King Mickey. For information about the Mickey that appeared in the Timeless River world, please see Mickey Mouse (Timeless River)
Mickey Mouse is the king of Disney Castle. He first appears in the short film "Steamboat Willie".
Before
Mickey was a student under Yen Sid. As seen in the Birth By Sleep secret video in Kingdom Hearts 2 Final Mix, Mickey was a witness to the fight, with Star Seeker in hand. He later met Ansem the Wise, befriending the king, and first met Xehanort.
Kingdom Hearts
Kingdom Hearts marks the first appearence of Mickey in the series.
In Kingdom Hearts, King Mickey had disappeared from his Castle home leaving a note instructing Donald and Goofy to "find the Key". In his journeys, King Mickey had passed the Corridor of Darkness at Traverse Town and found the Keyblade of the Realm of Darkness. At the end of Kingdom Hearts, he helps Sora to seal Kingdom Hearts to prevent the Heartless from escaping it.
Kingdom Hearts: Chain of Memories
In Chain of Memories, Mickey does not appear in Sora's storyplot (though he is mentioned) but instead appears in Riku's. In Riku's storyplot, he helps Riku to fight off the influence of Xehanort, who had made attempts to take over Riku's body as he did in the first Kindom Hearts.
Kingdom Hearts II
In Kingdom Hearts II, Mickey appears far more often then he had in the previous Kingdom Hearts games.
Mickey first appears to help Sora to fend off the Nobodies that attacked them in Twilight Town in Organization attire. After the battle, he handed Sora a money pouch and instructed him to visit his mentor, Yen Sid. Yen Sid revealed that Mickey's reasons for leaving Disney Castle in the first game was to investigate the mysterious outbreak of Heartless and the more mysterious Organization. Mickey makes several appearences throughout the game, and is even playable when Sora is defeated in certain boss battles. He wields an alternate version of the Kingdom Key.
At Hollow Bastion, Mickey revealed the truth about Ansem, but was relucant to reveal any info on Riku.