Metro is a British freesheet tabloid newspaper published by DMG Media. The newspaper is distributed from Monday to Friday mornings on public places in areas of England, Wales and Scotland (excluding public holidays and the period between Christmas Eve and New Year's Day inclusive). Copies are also handed out to pedestrians. In 2018, Metro overtook The Sun to become the most circulated newspaper in the United Kingdom.

Metro is owned by Daily Mail and General Trust plc (DMGT), part of the same media group as the Daily Mail and The Mail on Sunday, but in some areas Metro operates as a franchise with a local newspaper publisher, rather than as a wholly owned concern. While being a sister paper to the conservative Daily Mail, the newspaper has never endorsed any political party or candidate, and says it takes a neutral political stance in its reporting.

The Metro free newspaper concept originated in Sweden, where a publication of the same name was launched in 1995 by Metro International. British newspaper executives Jonathan Harmsworth and Murdoch MacLennan, from DMGT, were reportedly inspired by the idea and flew to Stockholm on a 'fact-finding mission' to develop their version. There were also reports in the late 1990s that both Metro International and Rupert Murdoch's News International were considering launching free newspapers in the UK that might prove a commercial threat to DMGT's businesses.

DMGT subsequently launched Metro, using the same name as Metro International's publications but with a different logo, on Tuesday 16 March 1999. This UK version of Metro had no relation to Metro International or its sister newspapers in other countries. Metro was launched initially as a London-only newspaper with an original print run of 85,000 copies, which were distributed via dedicated bins in London Underground stations. The newspaper was produced at DMGT's printworks and office complex at Surrey Quays in southeast London, away from the company's main newspaper office in Kensington, west London.

In the years following its launch, the paper's distribution was gradually expanded to other major UK cities, including Manchester and Birmingham. By February 2003, Metro had become operationally profitable for the first time. Its reach was extended further in 2004, becoming available in more urban areas, including Nottingham, Sheffield, Bristol and Bath.

Metro's circulation continued to rise in the following years, though readership temporarily dipped after the 7 July 2005 London bombings. There was a 1.8% decline – the equivalent of around 9,000 readers – in copies picked up in the weeks following the attacks due to a reduction in the number of people using London's public transport network, coupled with the temporary closure of some London Underground lines where Metro was distributed.

Following several years of expansion, in 2006 the newspaper's production was moved to DMGT's main newspaper offices at Northcliffe House in Kensington, west London. That same year the newspaper expanded further, launching in Cardiff and Liverpool in joint venture deals with Trinity Mirror.

At the time of its tenth anniversary in 2009, the newspaper was distributed in sixteen "major" UK cities and its circulation had grown to 1.3 million. Despite the increase in readership, that same year, management also closed five regional Metro offices in Manchester, Glasgow, Newcastle, Birmingham, and Bristol, which were responsible for producing regionalised arts, entertainment, and food pages, citing "challenging economic conditions".