Grimace began as a purple creature called the “Evil Grimace” in early McDonald's advertising.
The original character had four arms and was portrayed as a mischievous figure who stole milkshakes. McDonald's later simplified the design, removing two arms and changing Grimace into a large, friendly purple companion associated with Ronald McDonald and the wider McDonaldland cast.
That redesign changed both the character's personality and his role in the brand. Instead of being a villain, Grimace became a good-natured, somewhat childlike character who appeared in family advertising, restaurant promotions, and licensed merchandise.
People sometimes assume Grimace was originally created as a mascot for a particular menu product, but his earliest advertising identity was tied to stealing shakes. His unusual shape and limited facial features were deliberately broad enough to be recognizable to children in animated commercials.