The mayor of London is the chief executive of the Greater London Authority. The current mayor is Sadiq Khan, who took up office on 9 May 2016. The position was held by Ken Livingstone from the creation of the role on 4 May 2000, until he was defeated in May 2008 by Boris Johnson, who served two terms before being succeeded by Khan.
The role, created in 2000 after the London devolution referendum in 1998, was the first directly elected mayor in the United Kingdom.
The mayor is scrutinised by the London Assembly and, supported by their Mayoral Cabinet, directs the entirety of London, including the City of London (for which there is also the ceremonial Lord Mayor of the City of London). Each London Borough also has a ceremonial mayor or, in Hackney, Lewisham, Newham and Tower Hamlets, an elected Mayor.