You have your Dolores Umbridge's and Joffrey Baratheon's, and Hawke is a great obscure pick from Berserk. So I'm going to add another obscure one, from a shitty installment from an otherwise stellar JRPG series, Suikoden IV's Snowe.
One of the trademarks of the Suikoden series is great interaction and camaraderie among it's main characters. Even when the main character is silent, the story and characterization really drives home some strong bonds to make you really care about the people around you... making it that much more impactfull when an eventual death occurs.
Unfortunately Suikoden IV got dropped on it's head as a baby. Rather than build strong character ties through the story they drop all that and cut right to the chase by telling you straight up: "this is Snowe, he's your bestest friend in the whole world!" That would be this little prick right here:
You're the orphan kid, Snowe's the aristocrats son. As the game gets underway though rather than a friend he treats you more like your his charity case. He's an annoying little prick that gets by based on who his daddy is, covering up his incompetence through pure arrogance. The moment you prove to be the competent one and take command, he flies into a fit of rage and actually turns on you. Lines like "why does everyone love YOU?!" and "after everything I've done for you!" get thrown around. Through the course of the game he proceeds on a downward spiral trying to get back to you, with an eventual low point of attacking you in your hometown (I think it was) with a band of pirates.
Making things worse is the game continues on with the charade that this is your best friend and don't you feel sorry for him? In the other games if you can recruit all 108 characters you get a boon in the story, usually involving undoing the meaningful character 'death' I mentioned at the start. In Suikoden IV you get to find Snowe drifting on some wreckage in the middle of the ocean (IV uses it's a ship/island themed setting, like Windwaker), you pull him up he says sorry and you get to be friends again and finish the war together, yaaay!
A bad character is a bad character, but when I think of some absolute great friends and what you go through in some of the other installments, like Jowy and Nanami in Suikoden II, it just makes me hate the little prick even more.