Lucille is the leading lady in A Monster In Paris.
- Angelic Beauty: While she's not a real angel, Lucille's stage costume was made with this in mind.
- Childhood Friend Romance: She becomes a couple with Raoul, a boy she's known since they were children.
- Deadpan Snarker: Lucille has her moments of sarcasm, mostly towards Raoul.
- Fiery Redhead: Comes to a head when she tries to defend Francoeur from Maynott all by herself.
Francur is a giant singing flea, with a gentle disposition, and is the main character of the film.
- Amplified Animal Aptitude: He used to be a flea, but after being hit with what was ostensibly a growth potion he's not only a very capable singer, but demonstrates humanlike intelligence throughout the film. He also apparently keeps this intelligence when he turns small again.
- Big Creepy-Crawlies: Francur is a giant (albeit anthropomorphic) flea.
- Cute Monster: He's a giant mutated flea, but his looks fall squarely in the Ugly Cute category.
- Cute Mute: He can only "speak" in chirps and bleeps, but nobody cares because of how ridiculously cute it is. Did we mention he can sing, too?
- Disney Death: It looks like Maynott succeeds in killing him, but he actually went back to being tiny just in time to save himself. Later he reveals his presence to Lucille and Raoul and the monkey go back to the lab to make him big again.
- Gentle Giant: He's a 7-foot-tall flea monster, but he's a harmless 7-foot-tall flea monster.
- The Grotesque: He's a sweet-natured, kind, passionate seven-foot-tall flea. The number that shares the film's title is about how no-one (up to that point) can manage to see past his terrifying, monstrous exterior long enough to see his true nature, and how he's forced to hide himself because of it.
- Huge Guy, Tiny Girl: Lucille's an average-sized woman while Francur is a seven-foot-tall insect.
- Immune to Bullets: Francur takes a couple shots to the exoskeleton of his back without batting an eye. He avoids putting to the test what a bullet could do to his front, however.
- In a Single Bound: Being a giant flea, and since the Square-Cube Law is ignored as usual, Francur can naturally make tremendous jumps.
- Instant Expert: Francur learns to sing, dance and play guitar damn fast. He's later seen writing a piano piece!
- Like Brother and Sister: With Lucille, according to Word of God.
- Line-of-Sight Name: Francur gets his name from a sign in the alley where Lucille finds him.
- Meaningful Name: Francur means "honest heart".
- Nice Hat: He wears large, wide-brimmed hats as part of his disguise.
- The Speechless: Francur, outside of the songs, is incapable of speaking and chirps (or sings basic sounds) instead, which makes him even cuter. The set-up for A Monster in Paris (the song) implies he needs to hear music of any sort to be able to talk/sing.
- Vocal Dissonance: Let's be honest, nobody expects a 7-foot-tall flea monster to have such a high-pitched voice.
Raoul is an exuberant inventor and delivery driver.
- Childhood Friend Romance: He becomes a couple with Lucille, a girl he's known since they were children.
- Deadpan Snarker: He is very sarcastic.
- Decoy Protagonist: The movie starts out following him and Emile, but the focus shifts over to Francur and Lucille.
- Gadgeteer Genius: He invented and operates his Cool Car, Catherine.
- Heroes Want Redheads: Raoul has a big thing for Lucille.
- Jerk with a Heart of Gold: Raoul is a very pleasant and optimistic young man, with a bright and vivid imagination for inventing. He is however, very boastful, sarcastic, and quick to anger.
- Shipper on Deck: Raoul is very aware of Emile's affection for Maud and tries to help the two along in their relationship.
Raoul's main partner and best friend.
- Decoy Protagonist: The movie starts out following him and Raoul, but the focus shifts over to Francur and Lucille.
- Little People Are Surreal: Averted. While Emile is technically a little person, the film treats this characteristic with sensitivity, touching on how this impacts his self-esteem.
- Nice Hat: He wears a green bowler hat.
- Shrinking Violet: He's rather shy, especially when it comes to confessing his love to Maude.
- Took a Level in Badass: Émile directly fights Maynott and wins by using his wits!
Victor Maynott, otherwise known as Commissioner Maynott, is the main antagonist of A Monster in Paris.
- Antagonist Title: Francur isn't the monster of Paris, Maynott is.
- Big Bad: The main antagonist of the film.
- Cool and Unusual Punishment: His final fate. In a post-credits scene, Maynott is forced to endure off-key singing from his fellow inmates in prison.
- Captain Ersatz: Has a lot of similarities with Gaston.
- Humans Are the Real Monsters: He's a selfish, sociopathic glory hound perfectly willing to flat out murder innocent people to get what he wants. Lucille flat out tells him he's the real monster in Paris.
- It's All About Me: Even though he should be doing something about the flood and its victims, he prefers to let it drag on until he can figure out a way to use it to make him look good.
- Jerkass: Maynott is a greedy, pompous and wealthy police commissioner consumed by pride and ambition.
- Miles Gloriosus: Zigzagged. Maynott is a boastful braggart about what he'll do to "the monster" if he ever finds it. When he really does come face-to-face with the giant flea, instead of cowering, he really does try to kill it.
- Punny Name: If he won the election, he would be Mayor Maynott.
- There Are Two Kinds of People in the World: During his date with Lucille he tells her there are two kinds of people; the faceless masses and those with great destinies, such as himself. Later he insults Emile and Maud by telling them they're part of the faceless masses.
- Villainous Crush: It's obvious he's eager to have Lucille as a Trophy Wife.
- HeelFace Turn: He arrests Maynott after he realizes Francur is innocent.
- Heel Realization: Realizes that Maynott is monster and turns on him.
- Horrible Judge of Character: It's a wonder why Pate would waste his Undying Loyalty on serving the likes of Maynott.
- Pair the Spares: Pâté is implied to be in a relationsship with Lucille's aunt Carlotta at the end of the film.
- To Be Lawful or Good: Pâté is confronted to this choice as he realizes that Maynott is a bastard and is completely losing his sanity. He chooses the second option.
Émile's main love interest.
- Graceful Ladies Like Purple: An extremely refined, feminine woman who is always seen in purple clothing.