The Hamburglar was redesigned in 1985 from a villain into a friendly, childlike figure.
His original presentation emphasized theft and mischief: he was a small, scheming character who wanted to take hamburgers. In 1985, McDonald's changed the character's appearance and personality, giving him a younger and more approachable look for children's advertising.
This redesign is why images of the Hamburglar from different decades can look almost unrelated. The character retained his striped clothing and hamburger theme, but the older sinister portrayal gave way to a playful childlike figure. The change was part of McDonald's broader effort to refresh its McDonaldland cast.