The Magic Mirror, containing the Spirit of the Magic Mirror within, is a mirror is enchanted by the Queen to truthfully answer any question, albeit cryptically. It first appeared in Disney's Snow White and the Seven Dwarfs.
Kingdom Hearts χ
In Dwarf Woodlands, the Queen asks the Spirit of the Magic Mirror who is the most beautiful person in their land, but is told that she has been surpassed by Snow White.
When the Queen returns to the mirror under the belief that her huntsman has slain Snow White, the Spirit informs her that she was tricked, and that the Huntsman had provided her with only a pig's heart.
When Terra arrives at the Magic Mirror Chamber, he stumbles upon the Queen summoning the Spirit of the Magic Mirror. She demands to know who is "the fairest one of all", but to her fury, the Mirror informs her that that honor belongs to Snow White, and that she possesses a heart filled with light. Terra is intrigued by the mirror, and when the Queen notices him, she commands him to murder Snow White in exchange for letting him question the mirror about Master Xehanort's whereabouts. Hoping to avoid an incident like that with Aurora, Terra decides to simply ask the Princess, but when he finds her in the Flower Glade, a swarm of Unversed appear and she runs off in fright. Terra resigns himself to forcing the Queen to have the mirror provide his answer, and returns to her chamber.
Enraged by his disobedience, the Queen commands the Spirit of the Magic Mirror to consume Terra, and uses a magic potion to transform the Spirit of the Magic Mirror into an Unversed so that he can draw Terra into his realm and consume him. However, Terra subdues the spirit and returns to the Queen, who he forces to question the mirror about Xehanort. The mirror cryptically answers that Xehanort dwells "where war was waged upon the fells", implying the Keyblade Graveyard, so Terra leaves to continue his search.
After the Queen leaves the castle and curses Snow White with a poisoned apple, Aqua ventures into the chamber seeking clues to reverse the curse. The Unversed stirs and drags her into his realm as well, but she also subdues the spirit, who then proclaims the Queen's death and his own freedom, then vanishes into oblivion without providing Aqua any clues.
Once Dwarf Woodlands falls into the Realm of Darkness, the Magic Mirror goes with it. However, it appears the Spirit no longer lives in the mirror; the mirror itself appears to be manipulated by the dark realm. Aqua finds it near Snow White's glass coffin, having forgotten about it in the ten years she has been trapped. When she touches the mirror, and is pulled into the Magic Mirror's realm (the World Within) again by her own reflection. Several copies of the Magic Mirror steal Aqua's reflection, creating Phantom Aqua. Aqua defeats several copies of the phantom, eventually escaping the World Within.
The Spirit of the Magic Mirror takes the shape of a white theatre mask, though the light often falls on it in such a way to give it a two-toned appearance. It has high-set eyebrows and its "eyes" are empty holes, similarly to its mouth. The back of the Spirit's "face" is black.
The actual mirror is surrounded by chiseled tiles representing the twelve signs of the western Zodiac.
The Spirit of the Magic Mirror is not inherently evil, rather it is an obedient servant who will do whatever it is told. It is shown to have little to no emotion, which is emphasized by the dull, monotonous tone in his voice. Despite its loyalty to the Queen, it will refuse orders that it's unable to carry out, such as fighting an enemy. The Spirit also has the unusual tendency to talk in rhymes.
On its own, the Spirit of the Magic Mirror is an omniscient spirit who can see into all worlds.
As an Unversed, the Spirit of the Magic Mirror is an agile fighter, keeping its distance from opponents while shooting fireballs from its mouth. It also uses the mirror world to its advantage, creating replicas to confuse and attack opponents. It often slides horizontally across the ground while creating frame-by-frame reflections of its last few positions, inflicting damage to its opponents.
The Magic Mirror first appeared in Snow White and the Seven Dwarves as the Queen's counselor-of-sorts. The Mirror would appear at the Queen's request and would give her poetic answers to her questions (rather than saying Snow White, for example, he described her to the Queen). When the Queen asked the huntsman to bring back Snow White's heart in a box, the Mirror was able to identify the heart as the "heart of a pig" and so the Queen left to take care of Snow White herself, leaving what happened to the Magic Mirror after that a mystery.