McDonald's early small chef mascot was called Speedee. The character was derived from the Speedee Service System and represented the restaurant's promise of fast, standardized service.
Speedee appeared in the company's early branding before Ronald McDonald became the dominant advertising personality. The character was often shown as a chef with a hamburger-shaped head or related visual features, linking the mascot to the food and the restaurant's quick-service identity.
This question concerns Speedee as a branding character, not the 1948 creation of the Speedee Service System itself. The system was the McDonald brothers' method for streamlining food preparation and service; the mascot borrowed its name and communicated that idea to customers.
The character is also easy to confuse with later McDonaldland figures such as the Hamburglar, Mayor McCheese, and Officer Big Mac. Those characters belonged to a much larger fantasy cast introduced after Ronald McDonald had already entered advertising. Speedee belongs to McDonald's earlier visual identity.