George A. Romero's film about a helper monkey.
She's not a zombie monkey, but does kill people! Anyone who annoys her owner. Nice, eh? Not so nice when she gets jealous and attacks his girlfriend though!
I won't spoil anymore. Buy the DVD through the link above, or watch it for free here!
Below are Romero's other lesser-known fright flicks:
Season of the Witch (1973)
Two Evil Eyes (1990)