Legendary for it's ferocity, the Mountain Monkey was feared by man and beast alike. It was responsible for the slaughter of more livestock than the eastern timber wolf, black bear and mountain lion combined and the beast proved nearly impossible to kill. It is said that the head could live for a day or more after being severed from the body. The Mountain Monkey had little fear of man or musket and many trappers of the early eighteenth century failed to return from the Western Massachusetts forests that it called home.

The Nonotuck Indians had a saying, "If you meet the little devil of the hills, put aside your spear and your bow. You cannot defeat the beast with fire for eyes. Kneel down and sing your death song."