The Broadway favorite, who guest-starred last season as the Cut-Wife, will now be seen in the role of Dr. Seward, an American therapist who treats Vanessa (Eva Green) with an unconventional new approach. Also joining the cast is Shazad Latif, who will play the literary character of Dr. Henry Jekyll.

The third season of the series, which is currently filming in Dublin, will arrive on Showtime in 2016. Guest stars will include Christian Camargo as Dr. Alexander Sweet, a zoologist who strikes up an unlikely friendship with Vanessa; Sam Barnett as Dr. Seward’s mysterious young secretary; Wes Studi as Kaetenay, an intense, enigmatic Native American with a deep connection to Ethan (Josh Hartnett), who also becomes an ally to Sir Malcolm (Timothy Dalton); and Jessica Barden as Justine, a young acolyte to Lily (Billie Piper) and Dorian Gray (Reeve Carney).

The psychological thriller is created, written and executive-produced by three-time Oscar nominee John Logan and executive-produced by Logan's Desert Wolf Productions, along with Oscar winner Sam Mendes and Pippa Harris, both of Neal Street Productions.

The cast includes Hartnett, Dalton, Green, Reeve Carney, Rory Kinnear, Billie Piper, Simon Russell Beale and Harry Treadaway.