Professor Madcliffe was a character on Sam and Friends. He had a tall head, big eyes and a large moustache. He was usually very loud and energetic and often involved himself in the Esskay Meats commercials. His voice bears a resemblance to Guy Smiley from Sesame Street.
Introduced in 1957 (and originally interacting primarily with Footlight Theatre host Paul Arnold), Professor Madcliffe was the first Muppet character to use Jim Henson's own voice, rather than lip-synching to records or pre-recorded dialogue from others.