Larxene

 Origin:  Larxene was a nobody of a poor obdused girl from Hollow Bastion. Once a nobody, Xemnas fell in love with Larxene and had four children with her, Isa, Ienzo, Lea and Xion. One day, when her and Xemnas were visiting Lea, Isa and Ienzo's apprenticeship labortory an experiment went wrong destroying everyone there except for Xemnas. Xemnas resurrected his children and wife using darkness from the High Krawl.

 Death: 

Larxene was killed by her son, Axel, when he came to planet Malik to the castle she was residing in, asking questions about Xemnas. Larxene refused to answer any of them calling Axel weak. Axel in blind fury murdered Larxene and left Malik to find answers about his father.