Llanfairpwllgwyngyll or Llanfair Pwllgwyngyll (pronounced [ɬanˌvair puɬˈɡwɨ̞nɡɨ̞ɬ]) is a large village and local government community on the island of Anglesey in Wales. It is situated on the Menai Strait next to the Britannia Bridge and across the strait from Bangor. Both shortened (Llanfairpwll or Llanfair PG) and lengthened (Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch) forms of the placename are used in various contexts.
At the 2001 census, the population of the community was 3,040. By the time of the 2011 Census the population had increased to 3,107, of whom 71% could speak Welsh. It is the sixth largest settlement on the island by population.
The long form of the name, with 58 characters split into 19 syllables, is the longest place name in Europe and the second longest official one-word place name in the world. Although this name is generally stated to have been invented in the 1860s for promotional purposes, a similarly lengthy version was recorded as early as 1849.