Let’s get the obvious one out of the way: Millie Bobby Brown has to return as Eleven, even though she dropped a “Goodbye, Mike” in her parting scene in the Season 1 finale. Next year, we need to find out even more about her powers—and her limits. Why was she taken? Can Dr. Brenner brainwash her back to his side? Will she continue rocking the wigs or embrace her shaven awesomeness?