Theo Stevenson

Horrid Henry

Anjelica Huston

Miss Battleaxe

Ross Marron

Perfect Peter

Parminder Nagra

Miss Lovely

Mathew Horne

Dad

Siobhan Hayes

Mum

Richard E. Grant

Vic Van Wrinkle

Prunella Scales

Great Aunt Greta

Scarlett Stitt

Moody Margaret

Lloyd Howells

Rude Ralph

David Schneider

Soggy Sid

Kimberley Walsh

Prissy Polly

Billy Kennedy

Weeping William

Noel Fielding

Ed Banger

Jo Brand

Demon Dinner Lady

Helen Lederer

Rich Aunt Ruby

Rebecca Front

Miss Oddbod

Jack Sanders

Aerobic Al

Reuben Lee

Brainy Brian

Helena Barlow

Sour Susan

Nikita Mistry

Gorgeous Gurinda

Frank Kauer

Spotless Sam

Joshua-James Thomas

Goody Goody Gordon

Tyger Drew-Honey

Stuck-Up Steve

Tamsin Heatley

Madam Tutu / Fang (voice)

Dominic Wood

2C4S Presenter 1

Richard McCourt

2C4S Presenter 2

Zac Gabriel Werb

Tidy Ted

Keely Cat Wells

Alice

Kia Pegg

Vicious Vicky

Sam Davis

Keepy Uppy Boy

Freddie Rose

Schoolboy (uncredited)

Harvey Walsh

Schoolboy (uncredited)