MADMAN MARZ is the name of the legendary farmer-gone-mad in the 1982 cult, classic, horror film, MADMAN. The film was Produced by Gary Sales and Directed by Joe Giannone, who wrote the story and screenplay from an amalgem of Catskill Mountains campfire tales.
As it was told, MADMAN MARZ was a farmer who went beserk one night and ax murdered his entire family and then, covered in their blood, casually strolled into the local bar for a drink. When the locals learned what he'd done, they promptly lynched him and left him for dead swinging from a tree. The next morning, when they went to collect him-- he was gone, leaving only an empty nooseless rope. From then on it became local lore that if you spoke his name above a whisper while in those woods, he'd come and get ya'! The Legend of Madman Marz was born.
In the movie, the blood-fest begins after a smartass camper contrarily screams MADMAN MARZ aloud in the woods after being warned not to do so by the storyteller of the campfire tale.
Link on the internet movie data base Madman on imdb.com