Take the following information with a grain of salt, as it has in no way been confirmed by Ryan Murphy or the producers of "American Horror Story". That said, the word coming out of the "Spooky Empire" horror convention here in Orlando is that actress Naomi Grossman (who played Pepper in the second season of AHS entitled "Asylum") let slip that Rihanna (yes that one) is set to appear in the third season. "American Horror Story: Coven" will revolve around witches (duh) and be filmed in New Orleans. Multiple new cast members have already been confirmed, including Kathy Bates, Emma Roberts, Gabourey Sidibe, Angela Bassett, and Patti Lupone.
Being a rumor, we obviously don't have any more information as to what her role will be on the show, or whether it will be a lead or supporting part. My hunch is that it will end up being similar to Adam Levine's role in "Asylum", sort of a minor recurring role. Then again, maybe she'll be a member of the titular coven? Only time will tell.
Does the probable presence of Rihanna make you more or less likely to tune in for the premiere of "American Horror Story: Coven"?