Cladh Hallan is an archaeological site on the island of South Uist in the Outer Hebrides in Scotland. It is significant as the only place in Great Britain where prehistoric mummies have been found. Excavations were carried out there between 1988 and 2002, which indicate the site was occupied from 2000 BC.

South Uist is the second-largest island of the Outer Hebrides in Scotland. At the 2011 census, it had a usually resident population of 1,754: a decrease of 64 since 2001. The island, in common with the rest of the Hebrides, is one of the last remaining strongholds of the Gaelic language in Scotland. South Uist's inhabitants are known in Gaelic as Deasaich (Southerners). The population is about 90% Roman Catholic.