Sympathetic antihero/villain?

[Mythsage]

So this is a concern I've had in a few stories that I've been working on in my spare time.
A few of my protagonists are technically the villains of the story. (This includes my RPG maker projects, but since this is a more general question and a few of the stories were from plain text or Game Maker, I think this'd count as being non-RPG-maker-related enough. I hope. Sorry if it's not.) For instance, I've been messing around with creating a game where the protagonist is a wannabe/up-and-coming evil overlord in a mildly-cliche-parody fantasy world. (Not as parody-tastic as a game like Jay's Journey, but somewhat. I.e., orcs, elves, dwarves, etc.)
So, I must ask. When you're playing a character in a more story-based game (or reading from the perspective of a villain in a book), how far can the villain or antihero go before you really hate them? For instance, in above example, I plan of having the main character be dark and eeeevil, but with a few vaguely cartoonish/comedic overtones. For instance, he might think it better to beat the tar out of (or maybe kill) an exorbitant toll-taker, but at the same time will go into an indignant rant if somebody calls his robe a "poncho," loves small fuzzy animals such as squirrels, and is constantly put off by the rather unnerving/Genre Savvy musings of his lieutenant/henchwoman (who might suggest things such as "You know, you should see somebody about your monologuing problem. That sort of thing's not healthy. I had an uncle like that. Always talked to himself. He threw himself off a cliff. When we found him, he was a red smear on the ground. We didn't even have enough of him for a proper burial.").
So this, for me, raises two possible sources of problems for a reader.
1: The whole "Wanton destruction" thing, if taken too far, could possibly make the player/reader not care about the character. And I don't think I could give him a Doctor Horrible-esque problem against killing. The main idea I've had for negating this problem is giving the player a choice in the villain's actions (such as "Pay the Toll," "Try to Bargain," "Kill/Rough him up," or "Offer some 'Alternative' methods of payment (:P)"). But this is rather impossible in a book.
2: The comedy might seem a bit out-of-place, which is something that rather worries me. (For instance, I played a game where the protagonist, who wasn't even the villain, killed several innocent people over a prized racing bunny. While they were treating this seriously, I found it humorous, which ruined the effect of the world, which was intended to be really grim and dark and stuff.)
Thoughts?

[Lunarea]

Look up Dungeon Keeper and Overlord. Both are games that take the comedic approach and both deal with building your own army of evil to take on those pesky heroes that just have to try and ruin your evil reign. So, that approach certainly has appeal and draws an audience. There are two things that appeal to people: the novelty of playing for the "other" side and the comedy.

Little to no humor while playing the "evil" side might make your world more realistic/grim, but it might also be difficult for the audience to digest. To some degree, the audience identifies with the hero. They are disturbed by the evil and feel a sense of justice going into that final battle where the hero kicks butt. It might be interesting to see it from the other perspective, but it would also alienate the player a bit. We tend to find common elements with the heroes we play and (save for some) we'd find it hard to find the same common elements in someone who's sick/perverted/evil.

Adding at least some humor would be a good alternative, in my opinion. You'd lighten the mood and draw the audience in. They might be thinking "I wonder what joke he'll be making next" instead of "ooh, such evil person!", but they'll keep playing - and isn't that the whole point?

[Mythsage]

Thanks for the input. It's kinda nice to be able to bounce ideas off of people.
Yeah, I definitely think humor would soften the blow of the evil characters. Of course, making it so that they have semi-realistic goals (or at least mocking the non-realistic ones) would help.
Also, I was considering having the hero defeat the villain whenever the met or something like that, or at least at the end. Currently, though, I'm considering creating consequences for the villain's actions/outcomes in battles. For instance, if he decides to kill somebody who opposes him, people might react to him with hatred or fear, but if he has good PR, people would be more friendly. It'd require a bit more work, but I like writing dialogue and plots more than pretty much anything else.
Also, yeah, I've been meaning to play Overlord and/or Dungeon Keeper for a long time. I guess this gives me an excuse.