Extras is a British sitcom about extras working in television and film sets and in theatre. The series was co-produced by the BBC and HBO, and is created, written, and directed by Ricky Gervais and Stephen Merchant, both of whom also star in it. Extras charts the lives of Andy Millman, his friend Maggie Jacobs and Andy's substandard agent and part-time retail employee Darren Lamb, as Millman rises to fame. Extras has two series of six episodes each as well as a Christmas Special. The first episode aired in the UK on 21 July 2005 on BBC Two and on 25 September 2005 on HBO in the US. The second series premiered in the UK on BBC Two on 14 September 2006 and began airing in the US on HBO and in Australia on ABC on 14 February 2007. The Christmas Special aired on 27 December 2007 on BBC One and on 16 December 2007 on HBO. Both series are available on DVD in the UK and the US. The series is filmed in a more traditional sitcom style than the mockumentary style used by Gervais and Merchant in their previous series The Office. Each episode has at least one guest star; a television or film celebrity, who play what Gervais and Merchant have referred to as "twisted" versions of themselves; an exaggerated or inverted parody of their famous public personas.