Matilda (nicknamed "Mattie" or "Mat") is one of Reader Rabbit's best friends. She is a feisty young mouse who likes to do everything and wears a yellow shirt,a blue dress with white buttons and a blue ribbon on her tail (only from 1989–1994) . As a main character in Reader Rabbit Kindergarten, she finds some things that Spike is stealing. In Reader Rabbit: Playtime for Baby and Toddler she visits Reader Rabbit and goes into the book where it has so many fun worlds you can select. Mattie makes plenty of jokes! The song she sings is Mat's Song. She also appears in Interactive Math Journey (as a minor character) and in the video series “Read Now!”.In 'Reader Rabbit learn to read' Mattie goes to a fun fair but can't read the signs. Angry and annoyed, she wishes that there weren't any words, her wish comes true and she tries to reverse the spell but is unable to. She sits on a stage really sad about what she had done until some hamsters offer to help her with getting the words back, she is delighted and gets the words back in due time.
Matilda is naive, feisty and fun loving. Despite that, she is willing to help her friends whenever they need her. She is also very generous and kind-hearted.
She doesn't like being teased and gets really grumpy if anyone does so. If she gets told off, she gets upset
really sad. She sometimes makes bad decisions that have a massive effect and feels guilty afterwards.