Ruina Stoneheart is a villainous female witch from the Nexo Knights theme.
Ruina has a long bright blue hairdo, with the longer part over one side of her face. Her head is sand blue, with light blue lips, glowing yellow eyes, and a dark purple rock effect. One side of the head has an angry expression, the other has an evil smile. She sports a black torso with sand blue arms and black hands and a 2x1 slope piece as legs. Both the legs and torso have a dark purple rock effect with light blue electricity and white arcane symbols.
Formerly known as Wanda Moorington, Ruina was among the members of the Wizards' Council. She started to turn sinister by Monstrox's dark presence. She struggled to contain the darkness within. Her brother Merlok tried to save her, but was unsuccessful. Five years later, Merlok became Clay Moorington's secret guardian and trained him in the ways of knighthood, for fear that evil would run in Clay's veins as well.
- Wanda and Merlok are sister and brother.
- In the TV series, she is voiced by Heather Doerksen.