Lothian, also known as The Lothians, is a traditional region of the Scottish Lowlands, lying between the southern shore of the Firth of Forth and the Lammermuir Hills. It includes the city of Edinburgh, West Lothian, Mid Lothian and East Lothian. The principal settlement is the Scottish capital, Edinburgh. Other significant towns include Livingston, Bathgate, Linlithgow, South Queensferry, Haddington, Tranent, North Berwick, Musselburgh, Dalkeith, Bonnyrigg and Dunbar.

Historically, the term Lothian is used for a province encompassing the present area plus the Scottish Borders region. The name is related to the legendary British King Loth or Lot.

In the 7th century it came under the control of the Anglian Bernicia, the northern part of the later Kingdom of Northumbria, for a time, but the Anglian grip on Lothian was quickly weakened following the Battle of Dun Nechtain in which they were defeated by the Picts. Lothian's distinction from Northumbria is indicated in the survival of its original Brythonic Celtic name, used even by English Chroniclers. In 1018 AD Lothian was annexed by the Kingdom of Scotland.

Subsequent Scottish history saw Lothian subdivided into the shires of East Lothian, Midlothian and West Lothian - leading to the popular term "the Lothians". These were also known by the names of "Edinburghshire" (Midlothian), "Linlithgowshire" (West Lothian) and "Haddingtonshire" (East Lothian).