World D is the fifth and final secret world and the thirteenth and final world that was featured in the game Super Mario Bros.: The Lost Levels. Like the other secret worlds, it was left unused in Super Mario Bros. Deluxe. When Bowser is defeated at the end of World D-4, Princess Toadstool is saved, and, as such, Mario and Luigi beat the game.
Super Mario Bros.: The Lost Levels
Super Mario All-Stars