The following is a list of characters that appear in Horrid Henry, a British series of children's books written by Francesca Simon. It also includes names from the TV series of the same name and the 2011 film.

Main characters Horrid Henry Horrid Henry is the main character of the series. He wears a horizontally yellow striped light blue T-shirt, blue sewn jeans and green and white shell-toe shoes with yellow soles and laces. He is a very determined and relentless boy who believes that life is unfair, and fights against "the tyranny of adults", mostly anything children hate in a stereotypical view, from vegetables to school. Indeed, Henry's teachers, relatives, and babysitters in the series try their best to avoid him as they admittedly dislike his frequent antics. Henry is often rude, selfish, impatient, hot-tempered, impulsive, arrogant, and hardly ever learns from his mistakes, refusing to acknowledge them. He is also unafraid of telling people how much he hates them right to their faces. However, he is willing to act nice and collude with Moody Margaret and even his younger brother Perfect Peter, but only if it means he will get to have his own way. Because of his young age, however, Henry can get frightened by talk of ghosts or monsters, and is revealed to have a fear of needles in "Horrid Henry's Injection". He is also very imaginative, as he indulges in fantasies, usually transforming into terrifying creatures and attacking the source of his anger, and often has what he thinks is a "spectacularly wonderful idea" ("Eureka moments" in the TV series). In every story, there is something Henry has to get or do (or occasionally avoid doing) and the ensuing chaos is the consequence of this overriding desire. Whenever Henry thinks of a plan it is simply to get his own way, never to make trouble purely for its own sake. He is more often than not seen taking life very seriously and he sincerely believes in what he is doing. It has also been further hinted that deep down, Henry never really means to be horrid, and only acts that way as a wanting to get attention and a need to feel good about himself, particularly when dealing with Peter. He has a club called the Purple Hand Gang (a parody of the Black Hand Gang), with its headquarters being a fort hidden behind branches in Henry's back garden.

According to Francesca Simon, she got the idea for Horrid Henry when Judith Elliott, an editor at Orion Books, asked her to write a story about a horrid child. She also wanted to write about sibling rivalry and families where one child was considered "perfect" and the other "horrid". Henry was drawn with long hair and a striped shirt by Tony Ross in order to make him "recognisable from all angles". Henry is voiced by Lizzie Waterworth in the TV series. In Horrid Henry: The Movie, he is portrayed by Theo Stevenson.

Perfect Peter Perfect Peter is Henry's perfect younger brother, with whom he is in conflict. He wears a red jumper with a white shirt underneath, grey trousers, and brown lace-up shoes. He is often referred to as a "worm" or "toad" by Henry. Being quite mature for his age, he exhibits ideal traits including cleanliness, neatness, eating his vegetables, using his fork and knife, good manners and high academic prowess, resulting in his parents favouring him. He also often shows off how good he is, particularly when Henry is being reprimanded for his misbehaviour. Henry gets into trouble when Peter tells Mum or Dad that he has done something wrong, usually with the phrases "Mum/Dad! Henry's being horrid/mean to me!" or "Mum/Dad! Henry called me a worm/a toad/told me to shut up!" Despite being perfect, Peter is also naïve, as he believes Henry's odd stories without question. He can also be desperate for praise and attention and manipulates situations to his advantage. He is also the leader of the Best Boys Club.

In the TV series, Peter is revealed on several occasions to be, in reality, very whiny and spoiled. In addition to being desperate for praise and attention (e.g. getting his toys out just to tidy them again in "Horrid Henry Joins the Best Boys Club"), he tries to take credit for Henry's rare good deeds at times, as shown in episodes such as "Horrid Henry's Perfect Day" and "Horrid Henry: Horrid Headmaster". Peter seldom defies orders or complains about said orders, though as the series progresses, he indeed does defy adults or rules in revenge against Henry or while attempting to frame him. Despite all this, Henry will still help Peter out on occasion, such as rescuing him from a falling shelf in the cellar in "Horrid Henry: Trapped!".Horrid Henry TV series Episode #45: "Horrid Henry: Trapped!" (2 October 2007)

The inspiration for Peter came when Francesca Simon wanted to write about sibling rivalry and families where one child was considered "perfect" and the other "horrid". Tony Ross stated that he found Peter "challenging" to draw due to his innocent posture, so he mostly "put [the character's] hands behind his back and turned the face upwards". Peter is voiced by Emma Tate in the TV series. In Horrid Henry: The Movie, he is portrayed by Ross Marron.

Mum Mum is the mother of Henry and Peter. Due to Henry's behaviour, she appears to be quite stressed and irritable, and is strict towards him. She unfairly treats Henry most of the time, sending him to his room and banning him from watching television, pocket money, sweets and the computer, and believing him to have done terrible things that he has not done, as shown in "Perfect Peter's Horrid Day". Mum favours Peter over Henry and constantly praises him on his hard work and achievements, though will discipline him when needed. She usually wears a purple turtleneck cardigan with a pink shirt under it, blue sewn jeans, and magenta ballet pumps. Despite her strictness towards Henry and favouring of Peter, she does care for both her children and wants to know about their well-being. Tony Ross drew Mum with jeans and trainers to differentiate her from other mothers and give her a "trendier" look. In the TV series, Mum works part-time as the assistant manager of a library for Mrs Mossy.Horrid Henry TV series Episode #102: "Horrid Henry Meets B.B. Silver" (4 March 2010) She enjoys reading and fashion and is interested in beauty products like perfume. She also likes going in the cosmetics store "I'm A Lady".Horrid Henry TV series Episode #109: "Horrid Henry and the Perfect Plane" (4 September 2011) Mum is shown to be quite close to her sister, Rich-Aunt Ruby, though she is slightly annoyed by Ruby's wealth. She is voiced by Tamsin Heatley in the TV series, except for the episode "Horrid Henry's School Trip", where she is voiced by Sue Elliott-Nichols. In Horrid Henry: The Movie, she is portrayed by Siobhan Hayes.

Dad Silly Simon is the father of Henry and Peter. He wears a blue jacket with pockets, an orange turtleneck jumper underneath, brown trousers, and dark brown shoes. Like Mum, he has never trusted Henry to be well behaved. He also likes making Henry and Peter very healthy packed lunches. Peter often shows off to Dad by being perfect while Henry misbehaves. Specifically, he punishes Henry by banning the TV and/or the computer, but mostly resorts to cancellation or reduction of pocket money, as shown in "Horrid Henry's Hike". He shows favouritism when it comes to Henry and Peter. He tends to believe the best of Peter and the worst of Henry, as even if Henry was telling the truth (such as when Peter misbehaves), he will still dismiss it as "rubbish" and will find excuses for him; a good example being in "Perfect Peter's Horrid Day" when Peter sprays Henry with a hose deliberately, even chasing him around the garden, and he ended up telling Henry that he should have got out of the way when Peter was "watering the flowers".Horrid Henry TV series Episode #21: "Perfect Peter's Horrid Day" (16 February 2007) Although strict, he is much more tolerant and patient with Henry than Mum is by giving him second chances. He is often shown to be capable of distracting Henry enough that he behaves. Dad works as an office manager at Tingly Toothbrushes. His work boss is Big Bob, whom Dad does not seem to like as a friend, but he does take him seriously when it comes to working. In terms of the way that he gets treated by Bob and Henry, Dad prefers Henry's treatment instead of Bob's as he is very strict.Horrid Henry TV series Episode #16: "Horrid Henry Goes to Work" (10 January 2007) It is revealed that "Gross Class Zero" was his favourite show when he was a boy. At the end of "Horrid Henry and the Silly Siblings", it is revealed that his childhood nickname is "Silly Simon", and it is also implied that Henry gets his horrid streak from him, while Peter gets his perfect nature from Fussy Uncle Francis.Horrid Henry TV series Episode #128: "Horrid Henry and the Silly Siblings" (14 November 2011) He is voiced by Wayne Forester. In Horrid Henry: The Movie, he is portrayed by Mathew Horne.

Moody Margaret Moody Margaret is a girl who is portrayed as the primary main antagonist in the Horrid Henry franchise, and serves as Horrid Henry's competitive arch-enemy and next-door neighbour. She is very bossy and domineering, and is capable of releasing violent, piercing screams when her demands remain unfulfilled, as shown in "Horrid Henry and Moody Margaret" and "Moody Margaret Moves In". She wears a green cardigan with a white and lavender striped shirt underneath, a dark green skirt, frilly light lavender socks, and purple cap toe lace-up boots. Her parents spoil her and let her do anything that she wants. Margaret has a tendency to gloat about her various accomplishments in a ridiculously narcissistic fashion, looking down on others and domineering her friends and peers. True to this, she is resented by her best friend Sour Susan because of her rudeness, but Susan seems to have no other choice than to reluctantly obey Margaret's commands. Margaret leads the Secret Club in various plots formulated against Henry's Purple Hang Gang. In "Perfect Peter's Revenge", she is happy when Peter sends her a forged letter saying that Henry loves and wants to marry her, although it is unknown if Margaret truly has a crush on Henry or not. Margaret, however, occasionally assists Henry in his plans in episodes like "Horrid Henry's Horrid Revenge" and "Horrid Henry and the Big Dig". In "Horrid Henry: Rockstar!", her full name is revealed to be Margaret Millicent Maudita Smythe.Horrid Henry TV series Episode #105: "Horrid Henry: Rockstar!" (22 July 2011) Despite being a bit of a bully, Margaret is friends with most of the girls in her class. She is also very vain, frequently fussing over her appearance and trying to outshine her friends in fashion and toys. She is also quite athletic and loves to play football.

While Francesca Simon was in the process of creating Moody Margaret, she suggested a boy called Moody Martin, but her husband Martin Stamp did not approve of the idea as he thought that Moody Martin was too similar to Horrid Henry, the main character. Therefore, Simon made him a girl instead, and his name was changed into Moody Margaret. Simon stated in an interview that Margaret was based on herself at a young age and how she imagined Margaret Thatcher to have been as a child. Margaret is voiced by Sue Elliott-Nichols in the TV series. In Horrid Henry: The Movie, she is portrayed by Scarlett Stitt.

Rude Ralph