Director Bryan Singer confirmed earlier this week that the Game of Thrones star will join the cast of the upcoming sequel to X-Men: First Class, but did not state what role he would play.
Variety now reports that Dinklage will play "the main antagonist" in the film, which will be set more than 10 years after the events of First Class.
James McAvoy, Michael Fassbender and Jennifer Lawrence will reprise their roles from the first film, while X-Men alumni Hugh Jackman, Ian McKellen, Anna Paquin and Patrick Stewart will also appear.
The next film in the X-Men universe will be the Jackman-centric The Wolverine, which according to director James Mangold will portray its lead character "without a master, without a purpose. Kind of a soldier who is cut loose".
> Bryan Singer consults James Cameron for 'X-Men: Days of Future Past'
> Hugh Jackman on star-studded 'X-Men: Days of Future Past'
X Men: Days of Future Past will be released on July 18, 2014.
Watch Michael Fassbender discussing the sequel with Digital Spy below: