Mueller is wearing a tattered blue button down vest, mostly obscured by a yellow coat with a brown bowtie. He is wearing a graduation cap and holding a green ruler.
Always perfect with numbers and order, Mr. Mueller never let anything slide. Keep your numbers neat!
Mueller can teleport to a random location in the areas around him.
Mueller, like all Ghosts, can throw balls of Gloom on his enemies to harm them or to haunt buildings or objects.
- He's a member of the Wild Ghosts.