The programme is listed in Guinness World Records as the longest-running science fiction television show in the world, and as the "most successful" science fiction series of all time, in terms of its overall broadcast ratings, DVD and book sales, iTunes traffic, and "illegal downloads". It has been recognised for its imaginative stories, creative low-budget special effects during its original run, and pioneering use of electronic music (originally produced by the BBC Radiophonic Workshop). The show is a significant part of British popular culture; in the United Kingdom and elsewhere, it has become a cult television favourite and has influenced generations of British television professionals, many of whom grew up watching the series. It has received recognition from critics and the public as one of the finest British television programmes, including the BAFTA Award for Best Drama Series in 2006, and five consecutive wins at the National Television Awards since 2005, in the Drama category.

The programme originally ran from 1963 to 1989. After an unsuccessful attempt to revive regular production with a backdoor pilot in the form of a 1996 television film, the programme was relaunched in 2005, produced in-house by BBC Wales in Cardiff. The first series was produced by the BBC; series two and three had some development money contributed by the Canadian Broadcasting Corporation (CBC), which was credited as a co-producer. Doctor Who also spawned spin-offs in multiple media, including the current television programmes Torchwood and The Sarah Jane Adventures, the standalone K-9, and a single 1981 pilot episode of K-9 and Company.

The Doctor has been played by eleven actors. The transition from one actor to another is written into the plot of the show as regeneration, whereby the character of the Doctor takes on a new body and, to some extent, new personality. Although each portrayal is different, and on occasion the various incarnations have even encountered one another, they are all meant to be aspects of the same character. The Doctor is currently portrayed by Matt Smith, who took up the role after David Tennant's final appearance in an episode broadcast on 1 January 2010. A fifth series of the relaunched programme began on 3 April 2010, in which the Eleventh Doctor is accompanied by Amy Pond, portrayed by Karen Gillan.

Doctor Who first appeared on BBC television at 17:15 GMT on 23 November 1963, following discussions and plans that had been in progress for a year. The Head of Drama, Sydney Newman, was mainly responsible for developing the programme, with the first format document for the series being written by Newman along with the Head of the Script Department (later Head of Serials) Donald Wilson and staff writer C. E. Webber. Writer Anthony Coburn, story editor David Whitaker and initial producer Verity Lambert also heavily contributed to the development of the series. The series' title theme was composed by Ron Grainer and realised by Delia Derbyshire of the BBC Radiophonic Workshop. The programme was originally intended to appeal to a family audience. The BBC drama department's Serials division produced the programme for 26 series, broadcast on BBC One. Viewing numbers that had fallen (though comparably increased at some points), a decline in the public perception of the show and a less prominent transmission slot saw production suspended in 1989 by Jonathan Powell, Controller of BBC One. Although (as series co-star Sophie Aldred reported in the documentary Doctor Who: More Than 30 Years in the TARDIS) it was effectively, if not formally, cancelled with the decision not to commission a planned 27th series of the show for transmission in 1990, the BBC repeatedly affirmed that the series would return.

While in-house production had ceased, the BBC was hopeful of finding an independent production company to relaunch the show. Philip Segal, a British expatriate who worked for Columbia Pictures' television arm in the United States, had approached the BBC about such a venture as early as July 1989, while the 26th series was still in production. Segal's negotiations eventually led to a television film. The Doctor Who television film was broadcast on the Fox Network in 1996 as a co-production between Fox, Universal Pictures, the BBC and BBC Worldwide. Although the film was successful in the UK (with 9.1 million viewers), it was less so in the United States and did not lead to a series.

Licensed media such as novels and audio plays provided new stories, but as a television programme Doctor Who remained dormant until 2003. In September of that year, BBC Television announced the in-house production of a new series after several years of unsuccessful attempts by BBC Worldwide to find backing for a feature film version. The executive producers of the new incarnation of the series were writer Russell T Davies and BBC Cymru Wales Head of Drama Julie Gardner. It has been sold to many other countries worldwide (see Viewership).

Doctor Who finally returned with the episode "Rose" on BBC One on 26 March 2005. There have been four further series in 2006, 2007, 2008, and 2010 and Christmas Day specials in 2005, 2006, 2007, 2008 and 2009. The fourth series began on BBC One on 5 April 2008. No full series was filmed in 2009 although four additional specials starring David Tennant were made. A fifth full-length series began in Spring 2010, with Steven Moffat replacing Davies as head writer and executive producer.

The 2005 version of Doctor Who is a direct continuation of the 1963–1989 series, as is the 1996 telefilm. This differs from other series relaunches that have either been reimaginings or reboots (e.g., Battlestar Galactica and Bionic Woman) or series taking place in the same universe as the original but in a different time period and with different characters (e.g. Star Trek: The Next Generation and spin-offs).

The programme rapidly became a national institution in the United Kingdom, with a large following among the general viewing audience. Many renowned actors asked for or were offered and accepted guest starring roles in various stories.

With popularity came controversy over the show's suitability for children. Morality campaigner Mary Whitehouse repeatedly complained to the BBC in the 1970s over what she saw as the show's frightening or gory content; however, the programme became even more popular—especially with children. John Nathan-Turner, who produced the series during the 1980s, was heard to say that he looked forward to Whitehouse's comments, as the show's ratings would increase soon after she had made them. During the 1970s, the Radio Times announced that a child's mother said the theme music terrified her son. The Radio Times was apologetic, but the theme music remained.