Everybody Loves Large Chests (the series) by Neven Iliev is probably the most horrifying dark comedy fantasy I've ever read.  I laughed almost constantly throughout the first five books (what I've read) of this series... simply because it is just so far out there that it insulates you from the sheer horror of what is going on.

This series is focused on the antics and life of an aberrant, sociopathic, homicidal and ever-hungry mimic (yes, the treasure-chest monster) named Boxxy T Morningwood (yes, that's its name, lol).  It begins with the nearly brainless creature devouring a hapless adventure... and gaining a few levels and some intelligence in short order.

I say intelligence, but Boxxy is pretty much an idiot savant with a gift for homicidal mayhem, torture, and somehow always making out better than it should have been able to.  While Boxxy begins passively killing and eating 'tasty' adventurers and collecting 'shinies' in a dungeon, it quickly progresses to... doing the exact same thing (with added flair) outside the dungeon (well, with 'tasty' extending to just about everything along the way).  This ever-hungry idiot savant is somehow one of the single most hilarious protagonists I've encountered... anywhere.  Some of the things he gets up to (actually, most of them) are straight out of a Clock Up VN, and he only gets more horrifyingly evil as time goes on.  

Even though he does get more intelligent as he levels and evolves, his central interests forever focus on 'shiny' and 'tasty'.

Let's be clear, if I didn't make it so above... Boxxy is evil.  There is no redeeming value to him, despite what you might think of him at times.  He likes eating things, collecting shiny things, and killing to level up.  However, he proves that evil can be hilarious, if you know what you are doing.