Voiced by: Vanessa Paradis
Voiced by: Matthieu Chedid (French singing voice), Sean Lennon (English singing voice)
- Amplified Animal Aptitude
- Big Creepy-Crawlies: Francœur is a giant (albeit anthropomorphic) flea.
- Coat, Hat, Mask
- Cool Mask
- Cute Monster
- 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?
- Gentle Giant
- 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: With Lucille.
- Immune to Bullets: Francœur takes a couple shots to the exoskeleton without batting an eye.
- In a Single Bound: Justified since he's a flea.
- Instant Expert: Francœur 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: Francœur gets his name from a sign in the alley where Lucille finds him.
- Man in White
- Meaningful Name: Francœur means "honest heart".
- Nice Hat
- The Speechless: Francœur, 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.
- Tiny-Headed Behemoth
- Vocal Dissonance: Let's be honest, nobody expects a 7-foot-tall flea monster to have such a high-pitched voice.
- White Gloves
Voiced by: Gad Elmaleh (French), Adam Goldberg (English)
Voiced by: Sébastien Desjours (French), Jay Harrington (English)
Voiced by: François Cluzet (French), Danny Huston (English)
Voiced by: Philippe Peythieu (French), Bob Balaban (English)