Marvel has released some new behind the scenes photos for Thor: Ragnarok.
They include some new aliens, a monitor teasing the Thor and Hulk gladiator fight, and two that have Thor in chains with some type of horns behind him. MCU Exchange has speculated on what these may be, offering two possibilities:
"The darkness surrounding him would hint at him facing Hela in Hel, but looking closer it would remind comic fans more of Surtur’s horns from the comics. Could we finally see the fire demon make his appearance after all?"
It would make sense for Thor to make a trip to Hel since it is referenced with Ragnarok in Norse mythology, but Surtur has also been rumored to be making an appearance as well. The film hits theaters on November 3, 2017.