Baby Mario is Mario's baby self who first appeared in Super Mario World 2: Yoshi's Island. In this game, the Stork delivers Baby Mario and Baby Luigi to the Mushroom Kingdom. However, on the way, Kamek, an evil Magikoopa, steals Baby Luigi and the Stork. Baby Mario falls into Yoshi's Island and lands on the back of a green Yoshi. The Yoshi brings Baby Mario to the other Yoshies, and they decide to help Baby Mario rescue Baby Luigi from Kamek and Baby Bowser.
Baby Mario is a playable character in most of the Mario sports titles, as well as Mario Kart: Double Dash!!!. How Baby Mario exists in the same time period as Mario remains a mystery.
Baby Mario and his brother Baby Luigi, will star alongside adult Mario and Luigi in Mario & Luigi: Partners in Time for the Nintendo DS. They ride on the adults' shoulders, and a baby takes over when one of the adults runs out of HP.