Dark Bowser X is the fanmade X-variant of Dark Bowser from Mario and Luigi Bowser's Inside Story. He originates from MarioMario54321's Dark Star X videos. In SMG4, he makes a cameo in a guy's house on a TV where he, Dark Fawful X, and Dark Star X are seen bullying MarioMario54321. He also makes a cameo in SM64 Bloopers: The Idea block. where someone explains an SMG4 idea about Mario having to defeat a large overgrown monster in a city and Dark Bowser X is the monster depicted. Dark Bowser X makes several other cameos as well.