This fellow looks like an amalgam of several creatures: brown-coated rodent for hindquarters, a yeti upper half, and a bat-eared face of evil. Can it fly? Does it shoot iron spikes out of its tail?
I imagine that with a simple peeling back of its lips it could flash some hefty canines. This has identified this monkey as a bare-faced tamarin (Saguinus bicolor) otherwise called Pied Tamarin.