The Storm Blot was originally the true main villain of Epic Mickey before it was scrapped.
Not much information is known about the Storm Blot aside from it being an earlier incarnation of the Shadow Blot during development of the video game Epic Mickey. Concept artist Don Hamilton uploaded game art on the internet showing what appeared to be the Shadow Blot merged with Oswald the Lucky Rabbit terrorising Dark Beauty Castle.
Don wrote that the game's creative director Warren Spector wanted Oswald's jealously toward Mickey Mouse to grow to the point where he became a monster, leading many to believe that Oswald eventually combined with the Blot to destroy Mickey and escape the Wasteland.
However, Warren Spector has denied that Oswald was intended to become the Blot and additional concept art shows both Mickey and Oswald standing beside one another as they confront the Storm Blot at Dark Beauty Castle. It's unknown exactly why the Storm Blot was scrapped from the game, but it's likely to avoid depicting Oswald too negatively.
- Even if the Storm Blot was a scrapped villain in Epic Mickey, it was mentioned in Epic Mickey 2, when Abe says "But what Mickey didn't know was there another Blot, a Storm Blot, one that could destroy all of Wasteland," referring the Storm Blot from the first game.
- It could be that the Storm Blot is the embodiment of Oswald's jealousy and resentment towards Mickey Mouse, as well as Oswald's desire to have all Mickey's fame and friends. In concept art of the Storm Blot, it appears to have absorbed many Disney characters into itself, which could reflect on Oswald wanting Mickey's life for himself.