Man, I was wondering whose artworks I was seeing with all these interesting monkeys in 'em. I keep hearing from friends about how most primate species are "too human," or something to that effect, and they certainly get drawn that way an awful lot by others, but you definitely go the extra mile in showing how distinct monkeys can be, even showcasing different species in your other examples. As someone whose interest in anthropomorphism derives in large amount from showcasing how animal traits play out on the human form in a believable way, little artistic details like that go a long way in my book. I notice that this character and a few others seem to have "top-heavy" proportions, with relatively short legs for their body length. Is this a deliberate effort to showcase the difference in anatomy compared to humans, or just a stylistic convention of yours?

You also have quite the intense style of inking and coloring, especially in this picture. Lots of rough lines and directional streaks to convey action and intensity (though the pose itself is perhaps a bit static; maybe some more negative space would have helped?). I also like the alternations between solid and translucent black outlines as part of this effect, which helps to blend otherwise mostly flat colors into those directional elements in his fur and the streaks off his fist. I know this is just meant to be a sketch (your linework in other pictures can get a lot cleaner than this), but it's a good look for a sketch.

Aside from that... looking at the tags, I really need to get around to asking a certain someone I know about this character. Think I'll get on that now.