The skeleton musician who turns out to be Miguel’s great-great-grandfather is Héctor.
Héctor is introduced in the Land of the Dead as a witty, down-on-his-luck skeleton who needs Miguel’s help. He wants his photograph placed on an ofrenda so he can cross into the living world and visit his daughter, Coco, before she forgets him. This gives the film’s memory theme a personal emotional focus.
At first, Miguel believes that Ernesto de la Cruz is his great-great-grandfather because Ernesto’s guitar appears in a damaged family photograph. The mystery changes when Héctor reveals that he had a daughter named Coco. Miguel then realizes that Héctor, not Ernesto, is his actual ancestor.
The story also reveals that Héctor wrote songs later claimed by Ernesto, including “Remember Me.” Ernesto poisoned Héctor and stole his music, turning the apparent family mystery into a story about betrayal, stolen credit, and the importance of remembering loved ones.