Caillou ( kah-yuu, -⁠yoo; French: [kaju], stylized in lowercase) is an animated educational children's television series that aired on Teletoon (both English and French versions) – with the first episode airing on the former channel on September 15, 1997 – until the fourth season. After that, the fifth season channel was moved to Treehouse TV, and the series finale aired on April 17, 2011. It also aired on PBS and the PBS Kids Channel. A series reboot was announced in 2023 with a release date set to debut later that year on Peacock with 52 eleven-minute episodes, but was delayed for undisclosed reasons to February 15, 2024, with a batch of seven episodes.

Based on the books by Hélène Desputeaux, it focuses on a four-year-old boy named Caillou who is fascinated by the world around him. The series was produced in Canada by the CINAR Corporation (later Cookie Jar Entertainment), while the fifth and final season was produced in association with the South African studio Clockwork Zoo.

The series received initial positive reviews from critics and audiences. Contrarily, in the years following its release, the series saw a more negative reception and sparked backlash regarding its themes and writing.