The former Game of Thrones star and all around badass has officially signed on to appear in Zack Snyder's second Superman movie. He's joining Henry Cavill, Ben Affleck's first turn at Batman and the recently cast Gal Gadot as Wonder Woman, but no one is quite sure what his role will be.
The two leading theories has him as the movies potential villain, Doomsday, a Kryptonian monster who is most famous for killing Superman back in 1992. The other option is seeing him play Jusitce League regular, Martian Manhunter, making a Justice League movie all the more likely.