The names of the city and county of Derry or Londonderry in Northern Ireland are the subject of a naming dispute between Irish nationalists and unionists. Generally, although not always, nationalists favour using the name Derry, and unionists Londonderry. Legally, the city and county are called "Londonderry", while the local government district containing the city is called "Derry City and Strabane". The naming debate became particularly politicised at the outset of the Troubles, with the mention of either name acting as a shibboleth used to associate the speaker with one of Northern Ireland's two main communities. The district of Derry and Strabane was created in 2015, subsuming a district created in 1973 with the name "Londonderry", which changed to "Derry" in 1984.

Derry, officially Londonderry, is the largest city in County Londonderry, the second-largest in Northern Ireland and the fifth-largest on the island of Ireland. The old walled city lies on the west bank of the River Foyle, which is spanned by two road bridges and one footbridge. The city now covers both banks.