McDonald's began their McDonaldland marketing campaign in 1971 with commercials featuring a magical land inhabited by Ronald McDonald and a cast of characters inspired by their menu. Captain Crook and the Hamburglar would attempt to steal their respective menu items while the local sheriff "Big Mac", "Mayor McCheese" and Ronald McDonald would ultimately thwart their crimes. However, Sid & Marty Krofft of H. R. Pufnstuf (and many other Saturday morning staples) fame thought the real crooks were in the McDonald's marketing department. They felt McDonaldland and Mayor McCheese specifically were a direct ripoff of their Pufnstuf set and characters.
I recently found this McDonald's Thermo-Serv cup from 1978 featuring some of those characters.