What is the name of McDonald's fictional character who steals hamburgers?

The fictional McDonald's character who steals hamburgers is the Hamburglar.

The Hamburglar was introduced in 1971 as part of McDonald's expanding group of character-based branding. He was depicted as a small, mischievous figure whose central goal was to take hamburgers, especially Big Macs, from the restaurant's other characters.

His black-and-white costume, cape, hat, and exaggerated speech made him visually distinctive in television advertising and merchandise. The character was later redesigned with a more modern appearance, but the hamburger-stealing premise remained central.

The Hamburglar is often confused with other McDonaldland characters, including Mayor McCheese and Grimace. Those characters had different roles in the fictional world, while the Hamburglar was specifically associated with trying to grab burgers.