Madeleine Beth McCann (born 12 May 2003) is a British child who disappeared on the evening of 3 May 2007 from her bed in a holiday apartment at a resort in Praia da Luz, in the Algarve region of Portugal. The Daily Telegraph described the disappearance as "the most heavily reported missing-person case in modern history". Madeleine's whereabouts remain unknown, although German prosecutors believe she is dead.Madeleine was on holiday from the United Kingdom with her parents, Kate and Gerry McCann; her two-year-old twin siblings; and a group of family friends and their children. She and the twins had been left asleep at 20:30 in the ground-floor apartment, while the McCanns and friends dined in a restaurant 55 metres (180 ft) away. The parents checked on the children throughout the evening, until Kate discovered Madeleine was missing at 22:00. Over the following weeks, particularly after misinterpreting a British DNA analysis, the Portuguese police came to believe that Madeleine had died in an accident in the apartment and that her parents had covered it up. The McCanns were given arguido (suspect) status in September 2007, which was lifted when Portugal's attorney general archived the case in July 2008 for lack of evidence.Madeleine's parents continued the investigation using private detectives until Scotland Yard opened its own inquiry, Operation Grange, in 2011. The senior investigating officer announced that he was treating the disappearance as "a criminal act by a stranger", most likely a planned abduction or burglary gone wrong. In 2013, Scotland Yard released e-fit images of men they wanted to trace, including one of a man seen carrying a child toward the beach on the night Madeleine vanished. Shortly after this, Portuguese police reopened their inquiry. Operation Grange was scaled back in 2015, but the remaining detectives continued to pursue a small number of inquiries described in April 2017 as significant.In June 2020, police in the German city Braunschweig stated there was a new suspect in Madeleine's disappearance. In October 2021 the Daily Mirror reported that German public prosecutor Hans Christian Wolters was convinced that paedophile Christian Brückner abducted and murdered the child. German prosecutors hope to be able to bring charges in 2022.

Madeleine's disappearance attracted sustained international interest and saturation coverage in the UK, reminiscent of the death of Princess Diana in 1997. Her parents were subjected to intense scrutiny and baseless allegations of involvement in their daughter's death, particularly in the tabloid press and on Twitter. In 2008 they and their travelling companions received damages and apologies from Express Newspapers, and in 2011 the McCanns testified before the Leveson Inquiry into British press misconduct, lending support to those arguing for tighter press regulation.