Glummy Glooma is extremely gloomy and sad in his behaviors. He travels on a dark cloud and uses his scepter to bring gloom to whatever he targets. His effects are so extreme that it even temporarily affected the Rainbow King and The Wishing Tree. In "A Royal Stink", he began playing with Mila's pet Stinko and found a form of happiness, but was still gloomy.
Glummy Glooma looks slightly similar to his cousin, the Rainbow King. He is white in color and wears an indigo cap with an indigo cape. He travels on a dark rain cloud.
Glummy Glooma and the Rainbow King don't seem to get along very well, but the Rainbow King still shows patience towards his overabundance of gloom. The Rainbow King and Glummy Glooma could be seen repeatedly using their scepters to make an object gloomy, and then happy again.
Mila's pet Stinko doesn't necessarily make Glooma happy, but Glooma seems to find enjoyment by tossing a ball back and forth with him.