Deadline: One big break leads to another. I have learned that Fargo Season 2 standout Rachel Keller has been cast as the female lead in Legion, FX’s X-Men-universe pilot from Fargo creator Noah Hawley, Bryan Singer, Marvel TV and FX Prods. The 23-year-old Keller, who landed her first major role as femme fatale Simone Gerhardt in Fargo, was a breakout and a fan favorite. I hear she also impressed Hawley and FX brass who moved on to cast her in her first leading role. As with any other Marvel project, FX, Marvel TV and talent reps would not comment.