Horrid Henry is known for his mischievous ways and rebellious attitude, so when it comes to dressing up in a fancy dress costume, he certainly doesn't hold back. A fancy dress Horrid Henry costume would typically include a bright yellow and black striped t-shirt, paired with blue jeans and red sneakers. To complete the look, a messy mop of black hair and a cheeky grin would be essential. Accessories such as a slingshot or a toy spider could also be added to really capture Henry's playful and troublemaking personality. Whether he's causing chaos at a fancy dress party or just having fun with his friends, a fancy dress Horrid Henry costume is sure to turn heads and bring a smile to everyone's face.