Grimace was McDonald's purple mascot before the modern character lineup was simplified.
Grimace first appeared in 1971 as a character with four arms who represented milkshakes. McDonald's later redesigned him as the large, friendly, purple character most audiences recognize, with two arms and a simpler, less mischievous personality.
The character became part of the McDonaldland advertising world alongside Ronald McDonald and other branded figures. His visual design made him highly recognizable, even though the exact product association changed over time.
Grimace is sometimes confused with Birdie, who was associated with breakfast, or with CosMc, a later science-fiction-themed character. Those were separate McDonald's mascots. Grimace's defining branding feature is his purple appearance and broad, friendly shape.