Princess Toadstool

" Dear Mario: Please come to the castle. I've baked a cake for you. Yours Truly....Prince Toadstool(Peach). "- Super Mario 64

Princess Toadstool(currently known as Peach) is usually the damsel-in distress in games.

Super Mario Bros.
Princess Toadstool appears at the end of W8-4, where she congradulates him. She was kidnapped by Bowser.

Super Mario Bros. 2
Princess Toasstool appears as a playable character to defeat King Wart and save the Subcon.

Super Mario Bros. 3
Princess Toadstool was kidnapped by Bowser and the Koopalings.

Super Mario World
Same as Super Mario Bros. 3

Super Mario RPG: Legend of the Seven Stars
Peach is a playable character in Super Mario RPG.

NES Open Tournament Golf
She is Mario's partner.

Yoshi's Safari
Princess Toadstool send Mario on his quest.

Wrecking Crew '98
Princess Toadstool appears as an unlockable playable character.

Hotel Mario
Princess Toadstool is kidnaped again.

Mario's Tennis
She plays tennis.