- Horrid Henry: The protagonist of the series. He is a troublemaker who enjoys playing pranks and getting into mischief.
- Perfect Peter: Henry's younger brother. He is the opposite of Henry, being well-behaved and polite.
- Moody Margaret: Henry's older sister. She is moody and often gets annoyed with Henry.
- Mum: Henry's mother. She is kind and loving, but often gets frustrated with Henry's behavior.
- Dad: Henry's father. He is a hard worker who often comes home tired from work.
- Miss Battle-Axe: Henry's strict and grumpy teacher. She is always trying to catch Henry doing something wrong.
The Horrid Henry series has been translated into over 20 languages and has sold over 25 million copies worldwide. The series has also been adapted into several animated television series, as well as a live-action film.