Wizenheimer is a Koopa Wizard with a booming voice who acts as the main antagonist of the Super Mario World episode "Ghosts 'R' Us". His name is a portmanteau of the words "wizard" and "wisenheimer," which is slang for someone who makes clever remarks to display their own knowledge, typically in an arrogant manner.
Mario, Luigi, Princess Toadstool, and Yoshi first encounter Wizenheimer while searching the Enchanted Forest for Oogtar the cave boy, who is missing. After Luigi bumps into him, Toadstool recognizes him as the most terrible Koopa Wizard in the entire Dino World, scaring Yoshi off. Wizenheimer claims that the forest is his and whoever enters it becomes his prisoners, demanding that they enter a nearby Warp Pipe. Toadstool knows that it leads to his haunted house and refuses, but when Wizenheimer threatens the trio with a Bob-omb, they obey. Wizenheimer then shackles his new prisoners in his basement.
Wizenheimer later captures Oogtar by simply warping him into the dungeon after the caveboy arrives at his door and demands the princess and Mario brothers. Wizenheimer is later found in the basement when Yoshi ventures through the house to save everyone. The Koopa Wizard tries to attack Yoshi, but Yoshi, under suggestion from Oogtar, uses his tongue to eat his magic wand, rendering him powerless. Wizenheimer demands his wand back, to which Yoshi spits out a magic blast that frees his prisoners. Mario then jumps on Wizenheimer's head, sending him falling down the staircase.
A running gag in the episode involves Wizenheimer's name continuously being mispronounced by the other characters. Such names include: Wisenheimer, Wizen-wiseguy, Wiseacre, Wisen-whatever, Wizenmeanie, and Wisen-whatchamacallit.
Names in other languages
1 - Pronunciation of Wizenheimer's name is inconsistent throughout the dubbed version of the episode, even disregarding instances in the English script where characters are meant to pronounce it incorrectly.