Mum (Tamsin Heatley, Horrid Henry) TTS Computer AI Voice

Mum is the mother of Horrid Henry and Perfect Peter and is Dad's wife. She always tells Henry off, and hardly Peter because Henry refers to him as 'Goody-two-shoes'. She regularly says, 'Don't be horrid, Henry!' to Henry in the TV series, and 'Stop being horrid, Henry!' in the animated version. She usually sends him to his room like Dad. She does this by saying, 'Go to your room right now, Henry!'. Unlike Dad's, the series didn't reveal her first name. After what happened in "Moody Margaret Moves In", she disliked Moody Margaret.

She works part-time as the assistant manager of a book shop owned by Mr and Mrs Mossy. Every day, usually after her sons have left for school and her husband for work, Mum gets a bus to the book shop she works at. She can drive, but the family only own one car and Dad needs to drive to work as he works in another town.

In Horrid Henry: The Movie, Siobhan Hayes plays her, and in the TV series, Tamsin Heatley voices her.