The Apple Kid is a genius inventor who lives in Twoson. He makes his appearance in Earthbound. He helps Ness and co. throughout their journey, providing various items, such as the Pencil Eraser. He is only pet is a mouse, which is a large hint that he isn't very organized, since the mouse doesn't even have a name.
The Apple Kid is rivals with his neighbor, Orange Kid. Orange Kid is much more organized than the Apple Kid, and doesn't eat anywhere near as much.
Apple Kid's name is based off of the fruit. The sign for his house is an Apple, with the words, "Apple Kid" written on it.