There's been plenty of rumor and even some definitive evidence that Thor will be leaving our Avengers hanging in the fight against Ultron. With Ragnarok being an impending doom for Asgard, it looks like Thor has bigger fish to fry. It's always Asgardians before Earthlings with this guy.
While Thor is thought to be absent from the action in [Captain America: Civil War](movie:994409), could this mean we'll be seeing a different kind of Thor show up before [Thor: Ragnarok](movie:956858)? Someone who actually goes by the name Ragnarok?
Avengers 3 will lead directly into the events of Captain America: Civil War, and Thor's departure syncs up perfectly with Marvel's Civil War comic book storyline. When the Captain America vs. Iron Man battle got underway in the books, Thor was missing and presumed dead. But Iron Man had something up his sleeve, some Thor DNA!
Tony Stark is rather famous for thinking ahead - he is a self-proclaimed "futurist" after all. And over the various battles and adventures the Avengers have been in over the year, somewhere along the way Tony got his hands on a strand of Thor hair. And no, he didn't turn around and sell it on eBay.
Iron Man held on to this strand of hair for that just-in-case scenario - which presented itself when Civil War's Superhero Registration Act pitted him against Captain America and the anti-registration superheros. Looking to get some superhuman strength on his side he and Mr. Fantastic used the hair to create a cyborg Thor clone. As one does...
This clone was named Ragnarok and it ended up causing all sorts of problems when it went a little berserker during a clash between Cap and Iron Man's teams. It was a pivotal moment in the Civil War and served to greatly increase Captain America's animosity over Tony Stark. In many ways it was the point of no return.
Ragnarok had to be put down after his rampage and the whole ordeal gave Tony a bit of a much needed humbling. The events of the Thor clone are also what ended up getting Nick Fury to come out of hiding and get involved with the Civil War mess.
While the Cyber-Thor would most likely not be referred to as Ragnarok if he were to appear in the movie (far too much potential confusion for Thor 3) having another robot go crazy after the events of [The Avengers: Age Of Ultron](movie:293035) opens up plenty of thematic possibilities for the future of Tony Stark.
I wouldn't say that chances aren't great for a clone of Thor to show up in Captain America 3, but if you see Tony Stark pick up a stray hair in Avengers 2, you'll know what he has in mind.