Caillou is the four year-old main character of the program of the same name. He is inquisitive, adorable, curious, and his interests include cars and dinosaurs. Interestingly, Caillou was 2 1/2 years old when his baby sister Rosie was born, a 3 year old for the first 18 episodes of Season 1, but after the episode "Caillou's Birthday," he remains 4 for the rest of the series. He lives in a 2 story blue house on 17 Pine St. (as mentioned in the episode "Where I Live") with his parents Boris and Doris and pretty little sister, Rosie. Later installments show him attending playschool.
In the earliest episodes, he is normally seen wearing a dull grey shirt with a bright red collar, but for the remainder of the series he wears a yellow shirt with the same red collar. He wears blue longer shorts.
Caillou appears in all 229 Calliou episodes and has been voiced by Bryn McAuley (1997-2000), Jaclyn Linetsky (2000-2003) and Annie Bovaird (2003-present).