What was the name of McDonald’s 1970s character who promoted Shamrock Shakes?

Uncle O’Grimacey was McDonald’s 1970s character created to promote Shamrock Shakes.

He was presented as Grimace’s Irish uncle and appeared in seasonal advertising for the green-colored mint shake associated with St. Patrick’s Day. The character connected a limited-time product to a recurring mascot family, giving the promotion a stronger identity than a simple menu announcement.

Uncle O’Grimacey was introduced during the 1970s, after Grimace had already become part of McDonaldland. His name and design made the seasonal association immediately recognizable, while the character’s relationship to Grimace linked the promotion to the wider brand universe.

He is sometimes confused with Grimace himself or with generic St. Patrick’s Day advertising. The important distinction is that Uncle O’Grimacey was the specifically named relative used to promote Shamrock Shakes.