The programme's original cast included Lenora Crichlow as Annie the ghost, Russell Tovey as George the werewolf, and Aidan Turner as Mitchell the vampire.
On 11 November 2011, Russell Tovey announced that he was leaving Being Human during series 4 to work full-time on his other show, Him & Her,[1] and he appeared in the first episode only.
Damien Molony was introduced as vampire Hal, with Michael Socha's previously recurring role as werewolf Tom promoted to the main cast.
To promote the show, the BBC launched a blog, and on 22 December 2008, the BBC Being Human web page aired three prequel videos to introduce the three main characters: Mitchell's is set in the 1960s, George's is a video diary of his visit of Scotland, and Annie's shows her as a ghost terrorizing a couple who had moved into the house.
Lacey Turner played the recurring character Lia, a ghost encountered by Mitchell when he travelled to "the other side" in an attempt to rescue Annie from purgatory.
Series 3 story arcs included a prophecy that Mitchell would die from a "wolf-shaped bullet" (killed by a werewolf), Nina's pregnancy, and the resurrection of the cruel, manipulative vampire, Herrick.
[10] On 30 April 2011, actor Michael Socha, who plays the innocent young werewolf Tom, told the Derby Telegraph that he'd been asked by Toby Whithouse to appear in Series Four.
On 16 October 2011, SFX magazine revealed that Irish actor and 2011 Spotlight Prize nominee Damien Molony (a recent graduate of the Drama Centre London) had been cast as the new vampire Hal.
[15] Molony told the magazine in an interview that Hal is an upper-class, very English, well-dressed vampire for which the writers have laid out an extensive back-story.
[17] In his CultBox interview, Tovey said that the plot lines were "very spread out", that "a lot more happens", and that a number of new main and recurring characters had been added to Series Four.
[17] Dave Golder, writing for SFX magazine, concluded that Tovey's comments meant fans would see less of George and more of the new characters, and that Whithouse would be likely to reinvent the show with all these changes.
[18] The filmmakers returned to Barry Island to film season four in late July 2011, where they continued to use local man Gary Rowe's house as the group's bed-and-breakfast base of operations.
Michael Socha and Damien Molony reprised their roles as Tom and Hal,[22] and Kate Bracken joined the main cast as Alex.