The Robbing Leech is the main antagonist in the episode "The Headsucker's Moxy". He is a short, mute, formally-dressed man with a mouthful of sharp teeth, which he uses to latch on to people's heads in order to drain secret valuable information from his victims brains. The Leech then uses this information to steal his victims valuables and are seen with a series of bite wounds on their skin. After successfully draining his victims, they are rendered unconscious which allows him to claim their valuables without a fight and they complain of headaches and forget the valuable information they knew when they come to.

The Robbing Leech's first victim was the Townsville Bank Manger. After following him as he walks home from work, the Leech successfully catches and drains him to learn the combination to the bank vault to steal all of the money. The following night, the Leech targets a security guard at the Townsville Museum to learn the code to the inferred security system and steal all the artifacts. The next day the Leech drains a pirate and steals his buried treasure. Later that evening, the Leech sneaks back into the Townsville Museum to target the Sapphire Sultan, who was in possession of the worlds most valuable sapphire which he hides in a secret location, a secret which he was going to entrust with the Mayor. The leech then successfully brain drains the Sultan and renders him unconscious before deducing that the Sultan kept the sapphire wedged in his belly button, claiming it for himself and tipping his hat off to his unconscious fourth victim. The girls then arrive (having successfully deduced that the Sultan was the Leech's next target but arriving too late to save him) and make a plan to trap the Leech by tricking him into thinking that the Mayor is his ideal target.