Big Finish Productions is a British company that produces books and audio plays (released straight to compact disc and for download in MP3 and m4b format) based, primarily, on science fiction properties.

These include Doctor Who, the characters Judge Dredd and Strontium Dog from 2000 AD, Blake's 7, Dark Shadows, Dracula, Terrahawks, Sapphire & Steel, Sherlock Holmes, Stargate, The Avengers, The Prisoner, Timeslip, and Torchwood.

Founded in 1996, Big Finish in late 1998 began releasing audio plays adapted from the New Adventures, a series of novels from Virgin Books which had originally been licensed Doctor Who stories, but by then had become officially independent from the show and were based around the character of Bernice "Benny" Summerfield.

In 1999, Big Finish obtained a non-exclusive licence to produce official Doctor Who plays, beginning with the multi-Doctor story The Sirens of Time.

[7] In February 2008, Big Finish launched a new download service through their website, which would provide audio plays in MP3 format, free of any digital rights management.

[11] The Doctor Who audio plays have, to date, featured seven of the ten living actors to play the character of the Doctor in the series (Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy, Paul McGann, Christopher Eccleston, and David Tennant), as well as many of the regular supporting actors over the many years of the programme.

In February 2015, Big Finish announced that following a licensing deal with BBC Worldwide, they had been permitted to produce an audio series entitled UNIT: Extinction, starring Kate Stewart played by Jemma Redgrave.

In addition to this, Big Finish released a multi-doctor story featuring all surviving Doctors of the classic series and almost every companion in The Light at the End.

[19] In 2019, Big Finish reached its 20th anniversary of producing Doctor Who audios and released a special: The Legacy of Time which combined several spin-offs, including UNIT, The Diary of River Song, Bernice Summerfield and Counter-Measures.

Other spin-off series include Jago & Litefoot, featuring Henry Gordon Jago (Christopher Benjamin) and Professor George Litefoot (Trevor Baxter), characters from the 1970s storyline The Talons of Weng-Chiang; Counter-Measures, featuring a group of scientists featured in 1988's Remembrance of the Daleks; Vienna, focusing on an assassin named Vienna Salvatori (played by former Star Trek: Deep Space Nine actress Chase Masterson) who was introduced in the Seventh Doctor audio drama The Shadow Heart; UNIT, originally focused around the UNIT during the hiatus years of Doctor Who, starring the Seventh Doctor (Sylvester McCoy) and Elizabeth Klein (Tracey Childs, who first appeared in Colditz) and later became focused on UNIT from the revived series, featuring Kate Stewart (Jemma Redgrave and Osgood (Ingrid Oliver), as well as guest characters Jo Grant, River Song (Alex Kingston) and Doctor Chin Lee (Pik-Sen Lim, who first appeared in the Ambassadors of Death).

Two TV spin-offs from the Doctor Who universe have been continued in audio form by Big Finish: Torchwood and Class which has featured the return of several characters from the original cast: Gwen Cooper (Eve Myles), Owen Harper (Burn Gorman), Toshiko Sato (Naoko Mori), Ianto Jones (Gareth David-Lloyd), Rhys Williams (Kai Owen), Andy Davidson (Tom Price), Suzie Costello (Indira Varma), Captain John Hart (James Marsters) and Bilis Manger (Murray Melvin) have all reprised their roles in Torchwood.

Big Finish have also created several new characters of Torchwood in their continuation of the series from Miracle Day, most notably Tyler Steele (Jonny Green).

Other writers for Big Finish include Rob Shearman and The League of Gentlemen's Mark Gatiss, who have also written for the 2005 relaunch of the Doctor Who television series.

[24] Between 2002 and 2004, Big Finish released eighteen audio plays featuring characters from the British sci-fi comic strip anthology magazine 2000 AD.

The series would also feature many special guest stars such as The League of Gentlemen's Mark Gatiss playing Judge Death, Doctor Who companion actress Nicola Bryant (who would also direct 99 Code Red!)

[28] Big Finish also produced and sold 5 seasons of The Tomorrow People audios until renewed licence negotiations failed in late 2007, the range was withdrawn in total in December 2008.

[29] Big Finish has released audio dramas based upon other works as well, including Dark Shadows, Sherlock Holmes, Stargate, Captain Scarlet, Terrahawks, The Avengers and The Picture of Dorian Gray.

[30] In 2016, Big Finish produced and released its first series of The Prisoner stories, written and directed by Nicholas Briggs and starring Mark Elstob in the Patrick McGoohan role.