Kingdom Key

The Kingdom Key is the most recognizable Keyblade in the Kingdom Hearts series, and is the form used in almost all depictions of the weapon. It has appeared in every entry of the series to date, and has been confirmed to appear in the upcoming Kingdom Hearts: 358/2 Days. The Kingdom Key is the true form of Sora's Keyblade, and possibly all Keyblades, as it has been shown to be wielded by a large number of Keybladers. The Kingdom Key also draws out the true power of Sora's Keyblade, even though it is not the strongest keychain.

The Kingdom Key first appears when Sora receives the Keyblade during the destruction of the Destiny Islands, in Kingdom Hearts.

Appearance
The Kingdom Key is depicted as a classic skeleton key approximately 3.5' long, with a long silver keychain extending from the hilt, and a Hidden Mickey token on the end of the keychain. The blade and teeth of the keyblade are silver, the rainguard is blue, and the hilt is gold. The teeth of the keyblade form the outline of a crown which matches the crown charm Sora wears.

Users
Though the Kingdom Key is most usually related to with Sora, several others have used it, or copies of it, as well. Upon arrival to Hollow Bastion in Kingdom Hearts, The Kingdom Key is taken by Riku. This was short-lived, as Sora retrieved the Keyblade before fighting him (The Kingdom Key represented the concept of the Keyblade. When Riku took Sora's Keyblade, it appeared as the Kingdom Key, regardless of the Keychain attached at the time). This was the only case in which someone else held the actual Kingdom Key. Roxas is often seen with the Kingdom Key (when not using Oathkeeper and Oblivion). However, this is merely because he is Sora's Nobody, and that connection allows Roxas to have a Keyblade. Xion has also been seen wielding the Kingdom Key, although, it is believed to be a fake, possibly forged on the chains of Sora's memories. The exact origin of this Kingdom Key is unknown at this time. Mickey also uses a Kingdom Key, although his has inverted colors, the blade being gold and the handle being silver. Mickey's Keyblade comes from the Realm of Darkness while Sora's is from the Realm Of Light. At Sunset Horizons, Terra takes this Keyblade (though this is unknown why because Ven should have chosen the Kingdom Key instead and Terra, the Way of the Dawn, but it could be similar to how Riku was originally the Keyblade master, but then went to Sora).

Trivia

 * The Kingdom Key is the form depicted in all pre-rendered videos, as it is the only keychain which is possessed throughout each game; for example, no matter what keychain you use to fight World of Chaos, the cutscenes afterwards depict the Kingdom Key in its place.
 * The use of a Hidden Mickey as the keyblade's token may be due to Mickey being the main character in early plans for Kingdom Hearts.