The purple, blob-like McDonald's mascot that debuted in advertising in 1971 was Grimace.
Grimace originally appeared as a villainous character associated with stealing milkshakes, but McDonald's soon changed the character into a friendly, child-oriented companion. His simplified purple shape became one of the most recognizable designs in the company's character history.
Grimace belonged to the McDonaldland advertising universe, alongside figures such as Ronald McDonald and the Hamburglar. He is sometimes confused with Birdie or Captain Crook, who were also McDonald's promotional characters but had different designs and roles.
The character's unusual appearance helped distinguish him from conventional human mascots. Over time, Grimace became less defined by a specific product and more by his friendly personality and broad appeal in McDonald's advertising.