Mordecai Sledge is one of the villainous farmers in The Muppet Musicians of Bremen. He is the leader of a gang of villains, consisting of Lardpork, Mean Floyd and Caleb Siles, and the original owner of Leroy the Donkey. Mordecai has a particularly short temper, and it's sometimes difficult to understand what he's saying, which is usually a good thing, according to Kermit.
As the old Henson.com "Featured Creature" page explains, these farmers were "part puppet and part costume. In long shots, the character's head was worn as a mask by a performer inside the costume. In close-ups, he was manipulated like a hand puppet." The illusion was so convincing that the Muppet Workshop received a phone call from a Hollywood makeup artist who was convinced that Henson had discovered a new form of makeup.