The after-credits scene following Season 3 left us — in a word — shook, and we're endlessly relieved that some of the mystery will be cleared up in the now-confirmed Season 4. 

As a refresher, we saw inside what looked like a top-secret Russian facility. Two soldiers walk past cells looking for "the American," and eventually find him, then take the prisoner to visit a Demogorgon. Why? What? How? Who knows. 

But the biggest question plaguing us is: Who is the American?

We imagine it's probably not Alexei, since he's dead (thanks a lot, Grigori), and decidedly not American. That said, there are compelling theories that lead us to believe it could be Dr. Brenner, Barb, Bob, or even Hopper himself.

Stranger Things Season 3 is now streaming in its entirety on Netflix.