The Isle of Arran (ˈærən; Isle o Arran; Eilean Arainn) or simply Arran is an island off the west coast of Scotland. It is the largest island in the Firth of Clyde and the seventh-largest Scottish island, at . Historically part of Buteshire, it is in the unitary council area of North Ayrshire. In the 2011 census it had a resident population of 4,629. Though culturally and physically similar to the Hebrides, it is separated from them by the Kintyre peninsula. Often referred to as "Scotland in Miniature", the Island is divided into highland and lowland areas by the Highland Boundary Fault and has been described as a "geologist's paradise".
Arran has been continuously inhabited since the early Neolithic period. Numerous prehistoric remains have been found. From the 6th century onwards, Goidelic-speaking peoples from Ireland colonised it and it became a centre of religious activity. In the troubled Viking Age, Arran became the property of the Norwegian crown, until formally absorbed by the kingdom of Scotland in the 13th century. The 19th-century "clearances" led to significant depopulation and the end of the Gaelic language and way of life. The economy and population have recovered in recent years, the main industry being tourism. However, the increase in tourism and people buying holiday homes on the Island, the second highest rate of such homes in the UK, has led to a shortage of affordable homes on the Island. There is a diversity of wildlife, including three species of tree endemic to the area.
The Island includes miles of coastal pathways, numerous hills and mountains, forested areas, rivers, small lochs and beaches. Its main beaches are at Brodick, Whiting Bay, Kildonan, Sannox and Blackwaterfoot.
Most of the islands of Scotland have been occupied consecutively by speakers of at least four languages since the Iron Age. Therefore, the names of many islands have more than one possible origin, including Arran.