His name was given to him by Bowser Jr., who sought to use his powers to take over the Mushroom Kingdom. Although he is a major catalyst for the events of the game and forms an alliance with Bowser Jr., it is unknown if Spawny is evil.
HistoryEditSpawny started out as an ordinary Rabbid, but when he and many other Rabbids were transported to an unspecified location, Spawny stole the SupaMerge and used it to fuse other Rabbids with objects, doing so to create Rabbid Peach and Rabbid Mario. When Spawny enters the Mushroom Kingdom, the SupaMerge ends up meshing with him, turning him into what he looks like throughout the game.
Beep-0 informs Mario that the SupaMerge had been corrupted upon entering the Mushroom Kingdom, and he agrees to find Spawny. However, just as Mario and co. were about to catch Spawny on a tower overlooking Ancient Gardens, Bowser Jr. appeared and befriended Spawny. Mario and co. traversed the other three worlds and eventually defeated Bowser Jr. in his mech, Mecha Jr., retrieving Spawny in the process. However, the portal over the Mushroom Kingdom released a dragon named the Megabug, which captured Spawny and harnessed his power to unleash more beings. Mario and co. ended up defeating the Megabug and freeing Spawny and Bowser (who had also been corrupted by the Megabug). Spawny is then seen in the pre-credits scene, where he admires the statue erected in honour of Rabbid Peach.
When he was still a regular Rabbid, Spawny was mischievous, curious, and playful like his fellow Rabbids, while always causing trouble without thinking about the consequences. After his transformation, Spawny became timid, naïve, and childlike. This causes Bowser Jr. to take advantage of him, bullying him into using his abilities. Because his power comes from fear and stress, Spawny has little to no control of his abilities.