A baby-book design that stayed put
Caillou’s bald head began as part of his design in the books, before the character was presented as a growing toddler on television. As his age changed, that feature remained. The result is a character whose appearance does not follow the usual visual shorthand of a child gradually growing a full head of hair.
That difference can invite viewers to look for an explanation inside the story, such as an illness. But the baldness is a carryover from the character’s earlier book design, not a medical plot point. It is a visual detail inherited through the adaptation.
How a small detail becomes an identifier
When a character moves from books to animation, familiar features help audiences recognize the same character across versions. Caillou’s smooth head is one of those features: it makes him easy to pick out and preserves a direct link to the baby-book character, even as he appears older.
So the answer is less about what happened to Caillou than about what happened to the design. He grew up in the story, but the defining look he started with remained.
