LMFAO okay let's see.
I'm somewhat fascinated by the
Gigantopithecus ape which is thought to have once existed. Imagine seeing an ape that massive...Yeah, it's not technically a monkey but an ape, I hope that's ok.
I thought it was very cool how they portrayed king Louie as a
Gigantopithecus instead of the classic orangutan in
Jungle Book (2016). They apparently did this because they wanted to keep ecological consistency, since orangutans aren't found in India (where jungle book takes place), but Gigantopithecus fossils have been found there.
I'm also fond of the fictional mythical character Monkey King, originating from China. With increasing globalisation, the figure has been increasingly portrayed in Western media. Alternative names for monkey king are Sun Wukong, and Qitian Dasheng (齐天大圣). The latter translated means 'the great sage, heaven's equal' which I think is pretty much the coolest title ever. I have encountered the Monkey King in the videogames
Dota 2 and
Final Fantasy XIV. Perhaps you too have seen him show up somewhere.