Eduardo is a food item and a minor character in the SMG4 series.
It is a banana peel with a sombrero that Mario uses in SM64 Shorts: The Plumber Problem as a replacement for Luigi after he "betrayed" him. It tells Mario to kill Luigi and let hate flow through him. In response, Mario tries to prove to Luigi that he could be a better brother and ends up bombing his house. It is later revealed that Eduardo was possessed by Boo.
It later appeared in a cameo in Portal M4R10 - If Mario was in... Portal in the refrigerator that Mario was digging through.