The Skeleton Girl is a skeleton child that lives in the Land of the Dead with her brother the Skeleton Boy. The Skeleton Girl and her brother are seen at Victoria's wedding party. She and her brother are seen walking to the church with everyone else. She and her brother are last seen at Victor and Emily's wedding throwing flowers from their baskets.
She and her brother may have died from a sickness or virus because there is no sight of knife cuts on them, but they could've been killed a different way. She and her brother might be a reference to Jack and Jill.