The Hamburglar was introduced in 1971 as a McDonald's character obsessed with stealing hamburgers.
He became part of the McDonaldland cast, the fictional advertising world McDonald's used to connect its mascots. In his original portrayal, the Hamburglar was a small, mischievous character whose defining behavior was trying to take hamburgers from McDonald's and its other characters.
The character's appearance changed over time. Early versions looked more like an old-fashioned mischievous figure, while later redesigns gave him a younger, more streamlined appearance. Those changes can make historical images seem like different characters even though they represent the same mascot.
The Hamburglar was not McDonald's first mascot; Speedee came earlier, and Ronald McDonald became the central figure in the early 1960s. Instead, the Hamburglar functioned as a supporting character whose repeated hamburger-stealing gag made the food itself part of the advertising story.