The McDonald's character with a purple body who was introduced in 1971 is Grimace.
Grimace first appeared in McDonald's advertising in 1971. Early versions were portrayed differently from the friendly character most audiences later recognized, but the design was subsequently simplified into a large, purple, rounded figure with a cheerful personality.
Grimace became one of the central residents of McDonaldland, alongside Ronald McDonald, the Hamburglar, and Mayor McCheese. His simple silhouette and strong color made him easy to identify on signs, packaging, toys, and promotional material.
A common mix-up is to identify Grimace as a food item or to confuse him with the Hamburglar, whose defining visual feature is a striped burglar outfit. Grimace's name and design are part of McDonald's character branding, rather than the name of a menu product.