50 miles off the north coastline of Scotland, U.K.
Professor X, Moira MacTaggert
Points of Interest
State-of-the-art laboratories, detention cells, and computer banks; a hidden underground crypt outfitted with Shi’ar technology
Uncanny X-Men #104 (1977)
Agreeing with Charles Xavier's dream of peaceful coexistence between mutants and humans, Moira MacTaggert and Xavier turned her father's private island, Muir Island, into a world-class research facility for genetic mutations. She also created facilities that could house mutants whose powers were uncontrollable and/or dangerous to humanity, in hopes to cure them both physically and socially. Xavier went on to create the X-Men, but he often referred mutants to Moira's care, such as his own son, David Haller (Legion) and Jaime Madrox (the Multiple Man.) Moira had long kept her own son, Kevin, contained there, for his powers were too dangerous to be loosed. Magneto was also referred there, during the time the alien Stranger had devolved the Brotherhood of Mutants to infancy.
The X-Men first visited Muir Island when their enemy Eric the Red restored and freed Magneto, who proceeded to demolish the facility. The X-Men realized Magneto was being used as a distraction and fled, allowing Magneto to escape. Moira returned to the X-Men's headquarters, leaving Madrox and Havok to help repair the labs. She returned with Banshee when he had first burnt out his powers, and soon after, the X-Men had to return to face Moira’s son, now Proteus, who had escaped to threaten reality.
Rebuilding the facilities, Moira rededicated herself to full-time research, rarely leaving the Island. Over time, she offered sanctuary for Wolfsbane as well as for the X-Men and Morlocks wounded in an attack by the Marauders.
Soon afterward, the evil, disembodied Shadow King turned his attention to Muir Island. Gradually, he began to take mental possession of the entire island facility, including Moira MacTaggert and the mutants interned and hospitalized there. The Shadow King, through Moira, created a gladiator-like arena where the mutants could fight amongst themselves. About the same time, the X-Men were once again believed to have died, and the Shadow King-influenced Moira formed a band of interim X-Men with Muir Island’s mutants. The X-Men eventually reorganized and investigated the strange happenings on Muir Island, ousting the Shadow King with the help of Professor X.
When the original Excalibur was suffering a crisis of membership, several of their number joined the X-Men in a fight against the Acolytes on Muir Island. Afterward, the members of Excalibur asked if they could be based there, acting as an extension of Moira MacTaggert's work at the research facility as well as a force to fight against superpowered menaces. Excalibur remained based on Muir Island for all their subsequent adventures, although the team eventually disbanded when Captain Britain and Meggan were married months later.
During this time, Moira dedicated the majority of Muir Island’s resources to finding a cure against the deadly Legacy Virus. Eventually, however, the island was targeted by the Brotherhood of Evil Mutants, who wanted to use a strain of the Legacy Virus to attack humans. A number of X-Men tried to prevent this, but failed. Moira MacTaggert suffered mortal wounds during the attack, finally discovering the secret of the cure in her dying moments.
The fate of Muir Island upon Moira’s death remains unrevealed.