Cosette and Marius's Daughter

Cosette and Mairus's unnamed daughter appears in the last scene of the last episode and loses her hat while running through a field of flowers, very much exactly as Cosette did in the first episode. Cosette gives her back the hat but she thanks her father instead. Afterward, as Cosette did, she asks her mother about the necklace around her neck to which Cosette answers is a gift she inherited from her mother that will be passed to her when she grows up.

She seems to have inherited all of Cosette's appearances, although her hair is of a darker blond color, a sort of mix between her parents' hair colors.

Trivia

 * In the novel, it is unknown if Cosette and Marius ever had children, since it ended with the death of Jean Valjean.
 * While another novel, Cosette: The Sequel to Les Misérables (published 1995) has been written by Laura Kalpakian, this work remains non-canon, as it is purely based off of speculation.
 * The character remains unnamed, as she was only seen in the final seconds of the last episode of the series, and was never addressed by name. However, fans have speculated her to be named "Catherine", after the doll Valjean gifted Cosette not long before adopting her (and as some could put it, an homage to Valjean himself)