Treadaway ("The Lone Ranger," "Control," "Brothers of the Head") will star as Dr. Victor Frankenstein. His stage credits include Over There.
As previously reported, the cast will include Reeve Carney (Spider-Man Turn off the Dark), who will play Dorian Gray, Oscar Wilde's handsome and narcissistic protagonist. Timothy Dalton, Josh Hartnett and Eva Green have also been cast in the series.
The eight-episode drama focuses on some of literature's famed monsters, including Dr. Frankenstein and his creature, as well as characters from "Dracula" and "Dorian Gray." The show combines the classic horror origin stories as the monsters live with their alienation.
"Penny Dreadful" was created by three-time Oscar nominee John Logan ("Skyfall"), who will write and executive produce alongside Academy Award winner Sam Mendes and Neal Street's Pippa Harris ("Revolutionary Road"). Juan Antonio Bayona ("The Orphanage," "The Impossible") will direct the first two episodes.
The series will debut in spring 2014.