Ace Mikaelson is a guest character on Legacies. Ace is the hybrid son of Kol Mikaelson and Davina Claire and the older twin brother of Isabella Mikaelson. He is the grandson of Mikael, Esther Mikaelson, and Ms. Claire. He is the nephew of Freya, Finn, Elijah, Niklaus, Rebekah, and Henrik Mikaelson. He is also the cousin of Finn, Victoria, Hope, Miranda, Jenna, Nik, and Mason. He is also the grand-nephew of Dahlia.
Ace is a member of the Mikaelson Family and Claire Family. He has ties to the Salvatore Family, Gilbert Family, Petrova Family, and the Labonair Family. He is also the member of a powerful unnamed family of witches. He is one of the few children fathered by an Original Vampire.