True Blood is an endlessly entertaining television show. The first season was a quality murder mystery with some supernatural trappings and a creative combination of comedy, soap opera, and horror. The second season had bright spots, sure, but was mostly just a waste of my (and likely your) valuable time. The third season, while certainly much better than number two, still had a long way to go before it stacked up to number one.

Nevertheless, it’s still, as I said, endlessly entertaining. Which is precisely why any news about the fourth season is good news, in my opinion. Now, according to Deadline, not only do we have word regarding True Blood season four’s plot, but we also know who will be playing the season’s main antagonist: Harry Potter’s Aunt Petunia.

That’s right, Fiona Shaw, better known in the States as the horrible, selfish, and cackling Aunt Petunia, will be playing Marnie Stonebrook, a depressed and incompetent local medium and palm reader who becomes possessed by the spirit of a powerful witch. Originally, the show had intended to cast someone considerably younger, but Shaw, a longtime stage actress, was apparently just too good to pass up.

Fans of HBO’s True Blood won’t be totally taken aback by news that the main thrust of season four will involve witches, as there was plenty of foreshadowing in season three that indicated this would be the case – in addition to series creator Alan Ball saying it outright at Comic-Con:

“There will be witches and some of the characters we’ve known all along will have powers that maybe they didn’t know about.”

News about Fiona Shaw’s casting comes hot on the heels of Entertainment Weekly’s revelation about several new characters’ back-stories. In addition to Marnie, there will be the following new characters (with more likely to come):

  • Portia Bellefleur, sister to Sheriff Andy Bellefleur, a drop-dead gorgeous attorney-at-law.
  • Naomi, an Asian-American, lesbian cage fighter.
  • Queen Mab, a beautiful ruler of a fantasy kingdom with a terrible temper. (Could this be the same fantasy realm that Sookie Stackhouse continually found herself in during season three?)
  • Suzanne McKittrick, a Real Housewives-esque shapeshifter who throws massive parties for her shapeshifting brothers and sisters.
  • Emory Broome, an African-American (and fellow) shapeshifter.

Personally, I’m of the opinion that True Blood isn’t the best show on television, but it is a sort of show that’s not unlike every tawdry soap opera you’ve ever seen (don’t pretend you haven’t) – i.e., enjoyable even when it’s stupid beyond belief.

And yet, True Blood is not like Twilight or anything of that ilk. It’s funny, it’s clever, it’s subversive, and it’s incredibly self-aware. I don’t know about you, but I can’t wait for the next season. (As well as any True Blood movie that emanates therefrom.)

True Blood’s twelve-episode fourth season begins shooting early next year and is set to debut on HBO in summer 2011. Got any casting suggestions to go along with these new characters? We’d love to hear them.

Sources: Deadline, MTV’s Hollywood Crush, and Entertainment Weekly