The Mucus Man is a character that appears in the episode, "Global Grilling." He was constructed out of phlegm by Master Shake and Meatwad after they both became ill with a common cold. He comes alive due to the effects of Shake's nuclear "Char-Nobyl 6000" grill and forces the Aqua Teens to create more mucus creatures in an effort to take over the Earth.
In "Global Grilling", after the "Char-Nobyl" grill has punctured a hole in the ozone layer and caused polar ice caps to melt, resulting in a massive tidal wave, the Mucus Man busts through the Aqua Teens house, asking "Alright, who bought the grill?" Shake points to Meatwad, making him take the blame for purchasing the product. The Mucus Man then thanks Meatwad and states that the environment now is perfect, since he can now take over their "dumbass planet." It then cuts to 12 years into the future, showing multiple phlegm monsters whipping Frylock, Shake and Carl, urging them to produce snot, in order to conceive more disgusting mucus creatures. It is then shown that the Mucus Man has elected Meatwad the king of all the mucus beings, due to him allegedly buying the radioactive grill.