Throughout the series, Henry is shown as being a "horrid" child, indicated by the people around him, including his parents and teacher. He is shown to be around 10-11 years old. Horrid Henry's appetite, unlike his younger brother, includes mainly unhealthy choices, such as crisps, chocolate, sweets, pizza and chips. Henry seems to have a rejection to vegetables, and to school dinners. Henry prefers watching TV and playing computer games. Henry also has an obsession with pocket money, and he spends it all on sweets and comics. Henry often refuses to get into bed at bedtime, but hates getting up in the morning. Henry's main fear is injections. His hobbies include eating ice cream, watching television and he also has a main ambition to become "King Henry the Horrible", ruling the world. His favourite restaurant is Gobble and Go which was converted into a vegetable restaurant, The Virtuous Veggie, much to Henry's disgust. Henry is usually seen wearing a horizontally yellow striped blue shirt, with blue jeans and the usual green/white trainers. His preferred pyjamas are blue, with vertical white strips.
Henry's mother and father, have never trusted Henry to be well behaved, are extremely healthy, and always make something with vegetables for dinner. They also make healthy snacks for parties. Dad agrees with Mum almost all the time. They often yell at Henry, punishing him by banning him from watching TV and/or from using the computer, but mostly resort to cancellation or downward re-accession of pocket money, giving it to Perfect Peter. Peter on the other hand, rarely gets into trouble, and whilst Henry misbehaves, Peter shows off to their parents.
According to Henry, they have told him "millions of times" that he can never have another birthday party, but then agree to give him one more chance each year.
The vast majority of the time, Mum and Dad believe Peter rather than Henry, being best known for disciplining Henry, particularly with the phrase: "Don't be horrid, Henry!". They often force Henry to locations such as his room if he is not well behaved, or they simply say "GO TO YOUR ROOM NOW, HENRY!".