Born with numerous deformities, most notably a hunched back, Quasimodo serves as the bell-ringer for Notre Dame cathedral in fifteenth century Paris.

In addition, he was voiced by Tom Hulce in an Disney animated feature (1996); was parodied by Steve Lemme in the comedy Quasi (2023); and most recently was portrayed by Angelo Del Vecchio in a revival of the French-language musical Notre Dame de Paris.

In 2010, a British researcher found evidence suggesting there was a real-life hunchbacked stone carver who worked at Notre Dame during the same period Victor Hugo was writing the novel and they may have even known each other.

He was born to a tribe of Romani people (in the novel called égyptienne or 'gypsies'), but due to his monstrous appearance he was switched during infancy with an able-bodied baby girl, Agnes.

He is found abandoned in Notre Dame (on the foundlings' bed, where orphans and unwanted children are left to public charity) on Quasimodo Sunday, the First Sunday after Easter, by Claude Frollo, the Archdeacon of Notre Dame, who adopts the baby, names him after the day the baby was found, and brings him up to be the bell-ringer of the cathedral.

Looked upon by the general populace of Paris as a monster, he believes that Frollo is the only one who cares for him, and frequently accompanies him when the Archdeacon walks out of Notre Dame.

When Quasimodo sees Frollo smiling cruelly at Esmeralda's execution, he turns on his master and throws him to his death from the balcony in rage.

He then leaves Notre Dame, never to return, and heads for the Gibbet of Montfaucon beyond the city walls, passing by the Convent of the Filles-Dieu, a home for 200 reformed prostitutes, and the leper colony of Saint-Lazare.

The changes begin with how he became a ward of Claude Frollo; while in the novel, he is abandoned on the steps of Notre Dame, in the film that is where his mother is killed while protecting him.

In the beginning of the film, a Romani mother tries to bring the hunchbacked infant into Notre Dame with her for sanctuary, but the antizigan Judge Claude Frollo (Tony Jay) chases and inadvertently kills her.

Frollo attempts to drown the baby in a nearby well upon seeing his deformity, but the church's Archdeacon stops him and demands that he atone for his crime by raising the child as his son.

Over the years he raises Quasimodo with cruelty, forbidding him to leave the tower and teaching him that the world is a wicked, sinful place, and that the Parisian people will reject him due to his deformity.

Two of Frollo's guards ruin the moment by throwing tomatoes at him and binding him to a wheel to torment him, rousing a crowd of onlookers to join in.

Though saddened to see that Esmeralda has romantic love for Captain Phoebus rather than himself, Quasimodo cares for her enough to learn to respect her choice.

His love for Madellaine is briefly strained when he learns she was actually working on behalf of a greedy magician named Sarousch who plans to steal a particularly valuable bell called La Fidele, from Notre Dame.

In August 2010, Adrian Glew, a Tate archivist, announced evidence for a real-life Quasimodo, a "humpbacked [stone] carver" who worked at Notre Dame during the 1820s.

[9] The evidence is contained in the memoirs of Henry Sibson, a 19th-century British sculptor who worked at Notre Dame at around the same time Hugo wrote the novel.

"[9] Because Victor Hugo had close links with the restoration of the cathedral, it is likely that he was aware of the unnamed "humpbacked carver" nicknamed "Le Bossu" (French for "The Hunchback"), who oversaw "Monsieur Trajin".