Constance Langdon/Fiona Goode
Oh, did you think we were going to get through this post without bringing up Jessica Lange? We have no proof at all (and very little hope) that Lange will be back. But there are a lot of reasons to think she could, by some miracle, return to the fold.
First of all, Lange's characters in Murder House and Coven are pivotal parts of the story. Constance Langdon is one of the last characters we see in season one, and she's taking care of Tate and Vivien's demon child. It would be hard to bring back Murder House without her. Also, it's true that Fiona is trapped in Hell at the end of Coven, but wouldn't that add so much tension to the season if she somehow found a way to escape?!
There's more evidence! Of course, we have Murphy's aforementioned comment about the many returning fan favourites. Lange would have to be the top pick in this category.
Combine all that with the fact that Lange is still working with Murphy — she last appeared on his acclaimed 2017 series Feud — and that Murphy says she wants to come back when the timing is right. Well . . . I can't imagine a better time, can you?