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• Wufflebump (voiced by Che Grant) is a 5-year-old purple "rhinoceros" monster who lives in a volcano. He's the leader of the young monsters. He can be clumsy, as he often trips over his own tail. His Italian name is "Burlagiu".
• Icklewoo (voiced by Rosie Cooper-Kelly) is a 3-year-old yellow "goat" monster who lives in a flower windmill. She doesn't roar as loud as the others do, as she's shy. Her Italian name is "Minilu".
• Yummble (voiced by Max Pattison) is a 5-year-old orange monster with three eyes and legs who lives in a giant mushroom and loves to eat. He's the best friend of Wufflebump. Because of his appetite, he can have a hard keeping any kind of food where it is by gobbling it up and breaking the adults' rules of not eating them at the wrong times. He has tons of favourite foods. He is shown having super stretchy arms. Unlike the other students, he can’t sing out of tune and his singing is all in tune. His Italian name is "Iammi".
• Meepa (voiced by Ellie Gee) is a 4-year-old green alien monster who lives in a tree flat and has four hands. She likes to say her name twice ("Meepa! "Meepa!"), as she can never stop talking. She has a love for monster animals. She has the most flexible body out of anyone in the School of Roars. Her Italian name is "Mipa".
• Wingston Waftywing (voiced by Ben Guiver) is a 4-year-old blue "bat" monster who lives in a castle and is the smartest. He's depicted as the fastest monster in the school thanks to his wings, size, and energy, in the pilot, he is going to be female and named winona. His Italian name is "Wingy".
• Miss Grizzlesniff (voiced by Kathy Burke) is a pink-red tyrannosaurus rex-like monster and the teacher of the School of Roars. Her catchphrase is "Oh, my claws!" She's one quirky teacher.

Other

• Miss Sneezle (voiced by Jess Robinson) is the school nurse. Her room isn’t like any other school hospital - the students from the classroom can have squidgy pillows when they need a rest. The bandage bats can also sing a lullaby, which most of the monsters like, but Yummble doesn’t. The students can also get lollipops for being brave.
• Miss Twirlyhorn (voiced by Sarah Lancashire) is the headmonstress of the School of Roars.
• Mr Marrow (voiced by Andrew Scott) is the chef who works in the café at the School of Roars. In the episode Get Well Soon, he was the substitute teacher in the classroom.
• Mr Snapper (voiced by Andrew Scott) is a photographer that looks like a crocodile. He does not work at the School of Roars, but he visits when it is in need of a camera.
• Mr. Bogglelots (voiced by Andrew Scott) is the school optician. Out of all the characters, he has the most eyes.
• Mrs. Wufflebump (voiced by Jess Robinson) is Wufflebump's mother.
• Mr. Wufflebump (voiced by Alan Robinson) is Wufflebump's father.
• Growlbert (vocal effects provided by Alan Robinson) is Wufflebump and his parents' pet monster dog.
• Mr. Yummble (voiced by Andrew Scott) is Yummble's father.
• Mrs. Yummble is Yummble's mother.
• Yummble's baby brother
• Yummble's baby sister
• Meepa's mummy
• Meepa's daddy
• Icklewoo's mummy
• Icklewoo's daddy
• Mr. Waftywing (voiced by Andrew Scott) is Wingston's father. He works as a mailman monster.
• Mrs. Waftywing is Wingston’s mother. She has never appeared in the show because according to the episode Wingston’s Mummy, she has died, and Wingston misses her.
• Granny Waftywing is Wingston's grandmother.

Series 1

Series 2