The Hamburglar was introduced as a thief in McDonald's early McDonaldland campaigns.
The character was defined by his attempts to steal hamburgers, giving McDonaldland a playful conflict that children could easily understand. He appeared alongside other branded characters, including Ronald McDonald, Grimace, Mayor McCheese, and Birdie the Early Bird.
The Hamburglar's appearance changed substantially over time. The earliest version had a more exaggerated, somewhat sinister look, while later redesigns made him smaller, friendlier, and more cartoon-like. Those changes reflected McDonald's effort to keep its characters suitable for family advertising.
The Hamburglar is sometimes confused with Grimace because both were recurring McDonaldland figures. Their roles were different: the Hamburglar was the mischievous burger thief, whereas Grimace was generally portrayed as a large, friendly companion whose personality evolved across the campaign's history.