Torchwood is a British science fiction television programme created by Russell T Davies, a spin-off from the 2005 revival of Doctor Who which aired four series between 2006 and 2011.

The show shifted its broadcast channel each series to reflect its growing audience, moving from BBC Three to BBC Two to BBC One, and acquiring US financing in its fourth series when it became a co-production of BBC One and Starz. Torchwood is aimed at adults and older teenagers, in contrast to Doctor Who’s target audience of both adults and children. As well as science-fiction, the show explores a number of themes, including existentialism, homosexuality, bisexuality, and human corruptibility.

Torchwood follows the exploits of a small team of alien hunters, who make up the Cardiff-based, fictional Torchwood Institute which deals mainly with incidents involving extraterrestrials. Its central character is Captain Jack Harkness (John Barrowman), an immortal con-man from the distant future; Jack originally appeared in the 2005 series of Doctor Who.

The initial main cast of the series consisted of Gareth David-Lloyd, Burn Gorman, Naoko Mori, and Eve Myles. Their characters are specialists for the Torchwood team, often tracking down aliens and defending the planet from alien and nefarious human threats. In its first two series, the show uses a time rift in Cardiff as its primary plot generator, accounting for the unusual preponderance of alien beings in Cardiff. In the third and fourth series, Torchwood operate as fugitives.

Gorman and Mori’s characters were written out of the story at the end of the second series. Recurring actor Kai Owen was promoted to the main cast in series three, in which David-Lloyd too was written out. Subsequently, American actors Mekhi Phifer, Alexa Havins, Bill Pullman and Australian actress Dichen Lachman joined the cast of the show for its fourth series.

The first series premiered on BBC Three and on BBC HD in 2006 to mixed reviews, but viewing figures which broke records for the digital channel. It returned in 2008 where it aired first on BBC Two, receiving a higher budget; its uneven tone, a criticism of the first series, was largely smoothed out, and the show attracted higher ratings and better reviews.

The third series episodes worked on a higher budget and transferred to the network’s flagship channel, BBC One, as a five-episode serial, entitled Torchwood: Children of Earth. Although Children of Earth was broadcast over a period of five consecutive summer weeknights, the show received high ratings in the United Kingdom and overseas.

A fourth series, co-produced by BBC Wales, BBC Worldwide, and US premium entertainment network Starz aired in 2011 under the title Torchwood: Miracle Day. Set both in Wales and the United States, Miracle Day fared less well with critics than the previous series, though was applauded by some for its ambition. In October 2012, Davies announced that for personal reasons the show would enter indefinite hiatus.

All four series have been broadcast in Asia, Australia, New Zealand, Europe, and North America. Owing to the early popularity of Torchwood, various tie-in media were produced,^[5] including audio dramas, novels and comic strips. From its inception, the BBC invested in a heavy online presence for the series, with an alternate reality game running alongside the show’s first two series, and an animated Web series running alongside its fourth. The BBC continued to approve and commission licensed spin-offs after the show’s conclusion, including an audio series from Big Finish Productions.