Loki, chained to the three stones until Ragnarok. There’s no Sigyn because in Thor film, after what they did NOT do with Thor/Sif, I expect anything… Besides the muzzle in Avengers was a nice touch. I’d willingly pay for seeing this in Thor II, or Avengers II, or wherever. Just saying.
(Aaand, he’s not naked. In fact, he’s pretty much dressed link, but I didn’t want the pic to be that kind of interesting)