Harington joins Guy Pearce, Dakota Fanning, Paul Anderson and GoT actress Carice van Houten -- who stars as Melisandre, a.k.a. The Red Woman, on the HBO epic.
Brimstone, written and directed by Dutch filmmaker Martin Koolhoven, is an epic Western that tells the story of a young woman (Fanning) who is forced to survive against the machinations of an evil preacher (Pearce). Principal photography is already underway in Spain, Germany and Romania.
Although Brimstone is Harington's first big role after his GoT departure, it isn't his only recent foray into film. Harington's war-time drama Testament of Youth hit screens earlier this month, and the 28-year-old actor sat down with ET to talk about playing a character much different than Jon Snow.