The McDonald's character known as the thief in McDonaldland advertising is the Hamburglar.
The Hamburglar was introduced in 1971 as part of McDonald's fictional McDonaldland universe. His character was built around a playful obsession with hamburgers, and early versions used a more complex old-fashioned costume and speech pattern than the simplified character later seen in advertising.
The character appeared alongside Ronald McDonald, Grimace, Mayor McCheese, and other McDonaldland figures. Together, they created a fantasy setting that helped McDonald's communicate with children through recurring stories and recognizable personalities.
The Hamburglar is sometimes confused with Captain Crook, another McDonaldland character associated with stealing food. Their names and roles were different: the Hamburglar focused on hamburgers, while Captain Crook was linked to Filet-O-Fish sandwiches. The Hamburglar's name remains the more direct reference to McDonald's signature burger.