Grimace was originally introduced as a villainous purple figure who stole milkshakes.
When Grimace first appeared in McDonald’s advertising, the character had multiple arms and was presented as a milkshake thief. This early characterization made Grimace part of the playful conflict in McDonaldland commercials, alongside characters such as Ronald McDonald and the Hamburglar.
McDonald’s later changed Grimace’s design and personality. The character became a friendly, simple purple figure with two arms and a gentler role in family-oriented advertising. That redesign is the version most associated with the character in later decades.
The original role is often forgotten because Grimace’s familiar friendly identity replaced the earlier villain concept. Grimace was not originally a mascot representing a particular menu item; his defining early storyline was taking milkshakes.