legion tv show fx cast
Dan Stevens has been cast as David Haller. Legion is an American cable television series created for FX by Noah Hawley, based on the Marvel Comics character David Haller.
Cast. 1  Dan Stevens as David Haller / Legion. 2  Rachel Keller as Syd, the female lead. 3  Aubrey Plaza as Lenny, Haller's best friend.  Jean Smart as Melanie, Haller's therapist.