The Mayans had Hun Batz, the Chinese have the Monkey King, and the Hindus have Hanuman. Monkeys are also indigenous to Africa, so I'm assuming there are also simian gods from that region.
2 Answers
Thoth is a major god of Egypt who is sometimes depicted as a dog-faced baboon.
This is a form of Thoth known as A'an, God of Equilibrium. (Budge, The Gods of the Egyptians Vol. 1 p. 403)
You can find a list of African Monkey Gods here. The references all come from EA Wallis Budge’s Hieroglyphic Dictionary, which is dated 1920, so some of the scholarship may have been superseded by more recent research.
Budge also lists the "Aanau", the four ape-gods who judged the dead (p.114 in the linked text.)
The Baule people of the Ivory Coast worshipped the monkey god named Ghekre (aka Gbekre), who is a god of judgment (of the souls of the dead I believe).
There is also the Yoruba monkey god, Ellegba (aka Ellegua or Eshu), who stands at the crossroads as an intermediary between the Orisha and humans.
There is also Baba (aka Babi) of ancient Egypt (or Khemet), who is a god of virility, usually depicted with an erect phallus, and is said to be essential for male virility in the afterlife. He also is a punisher of those judged as wicked in the afterlife (by devouring them).
Generally, because monkeys display relatively greater intelligence than other animals, various African communities made them into symbols of wisdom, judgment, & discernment.
The website DukeZhou linked to is a great resource.