There's something to be said for a character who is so vile, so twisted, so amazingly hateable that an entire fan community is able to be in COMPLETE and TOTAL agreement that the character's demise should be slow and painful.
I've been involved in the Harry Potter fan community for a decade, so I know how people can disagree on characters. Everyone's got an opinion. I love Sirius and Luna, but there are people who find Sirius immature and Luna flat-out irritating. Which is fine. To each his own. So that's why it's always amazed me how much the Potter fans can agree so completely on one thing--we all HATE Dolores Umbridge.
In re-reading Order of the Phoenix, I'm reminded just how horrible Umbridge is. She does unthinkable, torturous things and obviously takes pleasure in people's pain. She's prejudiced and has an agenda at all times. She purposefully tries to make Harry and the other rebellious students as miserable as possible. She's just plain mean. She is, simply, the character we all love to hate.
I'd wager a fair guess that Umbridge is more hated than Voldemort (at least he gives interesting monologues).
A couple days ago, this idea was reinforced when I posted a status on Facebook saying how I always remember why I hate Umbridge so much when I read Order of the Phoenix. Within hours, several of my friends had either "liked" the status or made a comment expressing their own severe dislike of Umbridge.
Which got me thinking.
As a reader, I can't stand Umbridge. I laughed when she got carted off by the centaurs. I grit my teeth when she showed up to Dumbledore's funeral. I took great pleasure in reading a funny list of the "Top Ten Fates Wished Upon Umbridge," then printed it off to save forever. I really hate Umbridge. With an undying passion.
As a reader.
As a writer, I'm deeply in awe of the effect Umbridge has on people. I would love nothing more than to be able to write a villain so horrible that he/she gets a similar passionate response from readers. That would pretty much make my life.