Drawing Monsters are huge, chalk-like monsters introduced in All Chalked Up. They were created by Bubbles, when Him asks her to express her anger to Buttercup, who destroyed her chalks. After seeing the chaos she caused, she decided to as she said "express her anger in a positive way" by making the drawing monsters pretty and nice looking, making them not evil any more.
All four of Drawing Monsters are drawn by chalk sticks. They're quite huge, in four colors: red, green, brown and blue.