RIP Billy. We will miss seeing Dacre Montgomery and his shirtlessness grace our screens :(
Anyway, the BIG death that has everyone talking is fan-favourite Detective Hopper who heroically gives up his life after becoming trapped while trying to close the gateway between Hawkin and The Upside Down.
The screen cuts to black as Joyce (Winona Ryder) is forced fry the generator to break the connection between the two worlds and in doing so heartbreakingly loses Hopper.
This is where the hit Netflix series kind of reveals itself.
Hopper's body is nowhere to be seen which generally means NOT DEAD in TV language.
UPDATE (12/07/19):
TVLine has revealed David Harbour who plays Hopper is officially contracted to appear in season four and beyond but is completely up to creators Matt and Ross Duffer if they choose to keep him.
Even if dead, Hopper could still be cleverly incorporated through flashbacks and such.
Millie Bobby Brown also kind of hinted that Hopper is indeed alive while speaking to Entertainment Weekly.
"I just immediately wanted to put a camera on me and find the way I react and the way I reacted was pure devastation and sadness, and a distraught child that just lost her father or so she thinks. So it was definitely a raw emotion" said the 15-year-old actress.
Another big clue is the mid-post credits scene where Russian guards keep prisoners hostage to later sacrificed to an unidentified Demogorgon.
When they are choosing a prisoner to sacrifice, they walk past one closed door and say "not the American."
DING DING DING!
How convenient to show such a scene.
If it is Hopper, it will be interesting to see how he ended up in the Russian facility and how the hell he survived the whole thing.
This theory seems pretty accurate to be honest:
Also if Ariana Grande's mum Joan Grande believes Hopper is alive then yep, he is ALIVE.
Bring on season four!