Snow White is an original character from the 1937 Disney animated movie, Snow White and the Seven Dwarfs. She is one of the Princesses of Heart whose heart was required to open the final door in Kingdom Hearts.
Appearances
Kingdom Hearts
Snow White's world was destroyed by Maleficent. She was one of the first princesses to be captured and taken to Hollow Bastion.
In the game, if Sora seals the keyhole of Deep Jungle before sealing the one of Wonderland, Snow White is set to appear in front of the Disney villains instead of Alice. This may indicate she was the 4th Princess captured with Alice being 5th, Jasmine 6th and Kairi last.
When the darkness of the keyhole from Hollow Bastion spread throughout the world, Snow White and the other five princesses used their power to shield it inside in order to keep it from spreading throughout the universe.
When Kingdom Hearts was sealed she was returned to her own world.
Kingdom Hearts II
Although she did not appear in the game, Snow White's name was part of the password that allowed access to the DTD dataspace in Tron's world.
Birth By Sleep
Recently, a screenshot of Terra meeting Snow White has been released confirming that she will most certainly reappear. This time in her own world.
Abilities
Because Snow White is a Princess of Heart, her heart holds part of the ability to open the Final Keyhole that leads to Kingdom Hearts. She also has the power to hold back darkness using the light stored within her heart, a power which she and the other princesses can utilize alone (the exact way she fights off darkness is currently unclear).
In addition, her heart (along with that of the other princesses) can be used to create the Dark Keyblade, which allows the bearer to unlock anyone's heart.