Professor monkey appeared in a few episodes. He is the pet of Beppo and enjoys taking baths.
He is shown to be very smart, being able to understand English (and theoretically every other human language) but he only speaks in monkey-talk.
He has brown fur and peach-coloured skin and is average-sized for a monkey.
He also has several outfits including a white lab coat and a blue bathrobe. His first appearance was in Martha Doesn't Speak Monkey.