|The following information is from the Adventure Time comic book series. It may not be part of the same canon or continuity as the animated series.|
Sewer S. Wizard, middle name Stinkums, is a character who appears in Issue 12. He registers to take part in the wizard battle being organized by Finn, Jake and Marceline during their search for Ewlbo. Marceline beats him up after realizing that he was the one "getting all up in her sewer biz".
Sewer Wizard is a short humanoid with a bald head and scruffy beard, wearing a red toilet plunger on his head. His clothes and the documents that he tries to hand to Marceline are covered in splashes of suspicious green liquid.