1. The Post Credit Scene

The post-credit scene, obviously the biggest hint of them all. If you haven't seen it yet, go watch it! Three months after the battle at Starcourt, we watch as Joyce and her family move out of Hawkins. At the same time, in Kamchatka, Russia, we're shown a scene of prison guards bringing out a prisoner to face a Demogorgon. Just before they grab that prisoner, they pause at a different door. The Russian guard says 'No, not the American'

Most fans believe that Hopper is that American since that's what the Russians had called Hopper and Joyce for the whole season.

2. Body?

There was no body. Not even when the key exploded, he was gone already. When he threw Grigori into the key, it's likely that it malfunctioned and launched him through the portal rather than killing him. Since the other key is in Kamchatka, that's where he'd be. You know the rules of Hollywood: no body, no death.

3. Will's True Sight

There's a drawing in Will's bedroom. In the youtube video of the studio tour, they show a shot of the drawing on Will's wall. it looks EXACTLY like Hopper in a prison uniform. Remember, Will has true sight so he can draw those 'now memories' that he has, which would be one of their only ways of finding Hopper since Eleven's powers are gone. Not only that but in that drawing, he has a badge on his prison uniform. That badge read 403X, X in Cyrillic is the English equivalent of the letter H. H for Hopper.

The resemblance of the drawing to Hopper is uncanny.

4. Murray's Voicemail

The phone number Murray used in the show had an actual voicemail, "If this is Joyce – Joyce, thank you for calling. I have been trying to reach you and I have an update. It's about... it's about.. well, um, it's probably best if we speak in person. It's not good or bad, but it's something."

It could just be me, but it sounds like he might have been searching for Hopper for quite some time, and he's struck gold.

5. Kamchatka, Russia.

Murray's phone number, 618-625-8313 is also part of the coordinates for Kamchatka Russia. The first number 61.86258313, is the phone number. If you take that number, put each number into a pair and flip it (61 becomes 16, 86 becomes 68, and so on) you have 166.8523831. That Latitude/Longitude coordinate, 61.86258313, 166.8523831. That coordinate doesn't just lead to Kamchatka, it leads to the Penzhinsky District of the Kamchatka Krai, one of eleven districts in the Krai. Not only is Kamchatka where the end credit scene took place, but also where Alexei was seen in the beginning, attempting to build the Kamchatka Key.

6. Instagram

David Harbour who plays Chief Jim Hopper has been changing his Instagram profile picture to each digit of Murray's phone number/Kamchatka's coordinates every few days. If those numbers didn't have anything to do with his character, why would he post them?

7. Fletch Lives

While filming season 3, David Harbour has been referring to Hopper as 'Fletch' in several Instagram posts. Fans believe this may be a clue as to Hopper's fate since in the Fletch movie series, there is a movie titled as 'Fletch Lives'. Not only that, but he tags #SpoilersWithoutContext when he uses the name Fletch to refer to Hopper.

8. While I'm Away

David also posted on Instagram, a mock photo of him pretending to be Hopper. In that caption of the photo, he very specifically stated 'While I'm Away,'

Sounds to me like he isn't dead after all. He's just on a little vacation in Russia.

9. Or So We Thought

Millie Bobby Brown was doing an interview about her closing scene, reading the speech that Hopper had written. When asked how she prepared for that scene, she discussed that she hadn't read the letter before filming as she wanted her emotions to be raw. She described Eleven as "A distraught child who just lost her father— or so she thought."

Hmm.

10. See You In Season 4

Last but certainly not least, it has been reported that David Harbour's contract has been renewed for season four. Hallelujah. Hopefully, season four will end with a very happy ending and his long-overdue date at Enzo's with Joyce Byers.