The Muir Island Mutant Research Center was conceived by Moira Kinross MacTaggert and Charles Xavier during the early days of his efforts to assist mutantkind. The Center was located on an island off the coast of Scotland, land belonging to the Kinross Clan.
For a period of time while the X-Men were believed dead, from Uncanny X-Men #253-280, the staff and residents of Muir Island became an ad hoc team, using X-costumes that doubled as body armor and protective gear. They were mentally dominated by the Shadow King during this period, and the actual X-Men eventually reformed and were forced to battle their collected friends and allies. The group was referred to as the Islanders in Uncanny X-Men Annual #15 and X-Factor Annual #6.