Princess Peach Toadstool is the ruler of the Mushroom Kingdom and is a constant target of kidnapping by Bowser. The goal of most Mario games is for him to rescue the Princess. Peach is depicted as being much taller than Mario, which can be rather comical when she inevitably has to bend down to kiss him at the end of one of his adventures. She wears a pink ball gown and crown. In early games such as Super Mario World, her hair color used to be brown, but it was later changed to blonde to match her concept art. Her appearance in the GBA remake Super Mario Advance 2 is updated to match this. In North America, Peach was originally known as "Princess Toadstool," however, at the beginning of Yoshi's Safari, her name was changed to Peach, which was her Japanese name. Peach was a playable character in Super Mario Bros. 2 for the NES, where she had the ability to float for long distances. She was also playable (and the main character) in Super Princess Peach for the DS, which borrowed many elements from Super Mario World. She uses Mario's Palette.
Peach can be used in a normal level, as sprite 7C (which you must insert via the "Insert Manual" command), but it's not recommended that you do so. She'll glow a lot and slowly sink, and some other weird things will happen. For example, you can't move but only jump or spin jump. Then, the glitched sprite changes. Then mario glitches up, alternating between the left walk and right walk sprite. Then the end-of-game text appears, which is all glitched up.