Just real quick: I was lucky enough to correspond with RA Salvatore for awhile, and found out that, if anything, he hates Drizzt more than any of us ever could. The good folks at TSR kept having him pump out book after book, he got told how his characters would react by executives, and it just kept going downhill. The Forgotten Realms and everything in it was nothing more than an unfunny joke on gamers where the punchline was your wallet.
Personally, as far as TTRPG's go, I hate ERIN FRIGGIN' TARN more than anything. Talk about a holier than thou slitch with a stick in her bum. A friggin' know-it-all who contaminates an entire friggin' RPG with her existence. From her blathering on about good and evil without taking into account outside factors, to her slavish praise of anything she deems good, it was a sad sad day indeed for the Rifts system when we found out that she survived the Vampire Kingdoms.
But back to video games:
My most hated video game character is Batman from DCUO. He called me so much I was starting to wonder if I jilted him at the prom or something. And when Robin punked me out, I just chucked the game at that point.
But it was Statesman is the one I hate. He's from City of Heroes, and you'd have to be into the whole history and story of it as to why. But he's the biggest unhung villain of the entire piece, and everyone slobbers over him like a gold plated vagina. He's invaded sovereign nations, almost started nuclear wars, gotten the world involved in 2 interdimensional wars, and everyone throws in your face what a hero he is.
I hated the guy who he's a Marty-Stu of, and the way that Dev griefed people using him. Yeah, picking on 10th level characters with a GIANT MONSTER is really mature. I hated the way he's the most useless, ineffectual, piss poor excuse for a superhero EVER. I read the book on a bet and hated him even more. He's worse than 2 dimensional, he's the power fantasy of a fat kid and it showed.
His backstory, the Wiki, the novels, everything just makes him into a bigger and bigger douche, a complete power fantasy that sucks at even being the slightest bit heroic.