Geno is a character from Super Mario RPG and is probably the coolest one in it. He comes from the Star Road, a place way up in the sky where wishes are granted. When Smithy screwed it up, he came down to earth to try to recollect the road's broken pieces.

He arrived in a little kid's house, and looked around for a suitable body. He saw a Mario doll, a Bowser doll, a Princess doll, and a Geno doll. Fortunately, he chose to possess the Geno doll, because otherwise the game would have gotten very confusing. Shortly after, he joined Mario's team, adding his formidable spells and strength. After they defeated Smithy, he returned to the Star Road in a flash of semi-decent special effects.

It is doubtful that he will appear in any other games, which is quite a pity, as I liked him.