Joy (Andrea Martin) is briefly introduced in season two as a stylist on the set of Charles's "Brazzos" revival. The two finally agree to go on a date at the end of the last episode. A year later, when season three picks up, they're in a committed relationship. She tells Charles that it's OK for him to be happy that the show is over. In episode four, she tells Charles, "I'm gonna look out for you Charlie, just like I did with Ben Glenroy. He knew if he touched one hair on your gorgeous little head, he was gonna have to deal with me." That's some pretty damning evidence. Later, Mabel, Charles, and Oliver reveal that someone wrote "F*cking pig" in lipstick on Ben's dressing room mirror, and Joy reveals that it was her lipstick that was used. Probably all of this is a misdirect (it's quite early in the season to figure out the murderer), but it is compelling.
In episode five, Charles makes clear to Joy his suspicions that she's the murderer, and (understandably) she does not take it well. She reveals she was on backstage opening night — to cover a mysterious red mark Ben had on his face right before the curtains rose. She also breaks up with Charles.
Our verdict: Maybe guilty