World 3 (Super Mario Bros. 2)
World 3 (known as Chapter 3 in Yume Kōjō: Doki Doki Panic) is the third world of Super Mario Bros. 2. Like World 1, it is a grass land (though with a greater emphasis on secondary features, like a large waterfall, underground tunnels and a labyrinthine castle). The original world boss was Mouser, but in Super Mario Advance, he was replaced by Robirdo.
Bios from Super Mario Bros. 2 Guide
Bio for World 3-1
Bio for World 3-2
Bio for World 3-3