Grimace was originally called the Evil Grimace when the McDonald's character debuted in 1971.
The first version of Grimace was a large, purple, four-armed figure who was portrayed as a villainous character. In early advertising, he was associated with taking milkshakes, which explains why some accounts describe the original character as a milkshake thief.
McDonald's soon changed the character's role and appearance. The company removed the extra arms and presented Grimace as a friendly, child-oriented companion in McDonaldland advertising. The simplified purple design became the version most people recognize.
A common mix-up is assuming Grimace always had his familiar friendly personality. His later identity was substantially different from the original “Evil Grimace” concept. The character's transformation illustrates how McDonald's adjusted its fictional brand characters to make them more approachable for families.