Space Mario is one of Mario's Power-Ups. It first appeared in Super Mario Universe: Wormhole Ahead. He can throw Black holes that suck up enemies besides from Koopalings and Bowser. He obtains this form by obtaining the Space Flower. He can also turn into a black blob and munch up anything.
Super Mario Universe: Wormhole Ahead is the first game in which Space Mario appears. There are several levels based around the usage of this form.