Dr. Moria MacTaggert is one of the world's leading authorities on genetic mutation in the Marvel Universe. She is Professor Charles Xavier's colleague, confidante, and was also once his fiancee. Born Moria Kinross to Scottish parents, she met and fell in love with Xavier while they were attending graduate school at Oxford University. Unfortunatley, she ended their engagement when she was forced into marriage with the late politican Joseph MacTaggert. Thereafter she had a son named Kevin, a mutant who would later be called Proteus. She also raised the orphaned mutant Rahne Sinclair (Wolfsbane), who considers her a second mother.

Her research station is on Muir Island, Scotland, off the northern coast of Cape Wrath. She has, among other facilities, a hospital, a large computer center, a large research center, and confinment areas for mutants considered to be dangerous. Recently she has redirected her energies into finding a cure for the Legacy Virus, and is the only non-mutant to have ever contracted the disease.