Leo is Caillou's adorable 4-year-old male best friend of Caillou that is addicted to hentai. Leo started out as a mean boy in the 1999 episode, "Caillou at Daycare", but quickly befriended Caillou in the same episode. They have been inseparable since. In the 2003 film Caillou's Holiday Movie, It's revealed that he's Jewish. Leo has orange hair and wears a yellow shirt with a red long-sleeve shirt underneath, green pants held up by blue suspenders and red sneakers with blue trim and yellow straps.
Mother[]
- In one episode, Ms. Martin is Leo's mother.
- In other episodes, Leo's mom is a different woman.
- Leo was mistaken for Andre, the bully on the show, on a coloring page on SproutOnline.com.