Monsieur Thénardier is the husband of Madame Thénardier, the father of Éponine, Azelma, Gavroche, and two unnamed sons, and a temporary caregiver for Cosette. A petty criminal, Thénardier is depicted throughout the novel as greedy, abusive, and unscrupulous. Thénardier initially runs a local inn with his wife, but loses it due to bankruptcy and is pushed into destitution. As a father and caretaker, Thénardier is cruel, subjecting Cosette to laborious household chores, little food or luxuries, and physical and verbal abuse, and sending Gavroche to live in the streets.

Throughout Les Misérables, Thénardier seeks to make money by robbing or blackmailing many of the novel’s characters, particularly Jean Valjean. After a failed attempt to rob and murder Valjean, Thénardier is arrested and sentenced to prison. With the help of Gavroche, Thénardier escapes and once again seeks to swindle Valjean. When Valjean saves Marius’s life by carrying his injured body through the sewer, Thénardier mistakenly perceives this as an attempted murder and later sells this information to Marius for money. Marius, who at the time was committed to cutting Valjean out of his and Cosette’s life due to Valjean’s criminal past, understands Thénardier’s confession for what it is—proof that Valjean was the person who saved Marius’s life. Thanks to the Thénardier’s misunderstanding, Marius, Cosette, and Valjean are able to mend their relationship right before the latter’s death. This marks the final moment, in a series of moments, in which what Thénardier lacks in understanding or knowledge he more than makes up for in greed. While not the primary antagonist, Thénardier is nonetheless a villain, more straightforwardly so than the novel’s main antagonist, Javert. Unlike Javert, Thénardier’s character development remains static throughout the narrative. He ends the novel by escaping to America to become a slave trader; Hugo highlights this lack of development by characterizing Thénardier as “incurable.”