Mr Fib and Little Miss Surprise will become the latest characters to feature in the beloved Mr Men picture book series.

More than 50 years since Mr Tickle, the first title in the series, was published, the books will join the classic range this autumn. The new books have been written and illustrated by Adam Hargreaves, who took over the running of the Mr Men and Little Miss cartoon empire after the death of his father, Roger Hargreaves, in 1988.

Mr Fib is a round, green character with a blue top hat who “fibs to impress people”, and the story will follow him as his fibs get out of hand and upset his friends. Meanwhile, the Little Miss Surprise book is about a purple, pink-haired character who “never knows what each day may bring” and takes Mr Quiet on a surprising day out.

“Mr Fib has been rattling around in my imagination for a long while,” Hargreaves said. “Little Miss Surprise, of course, popped into my head right out of the blue!”

Emily Campan, the publisher of the books in the UK, said she and her colleagues were pleased that the new characters “reflect the world and personality traits children might encounter in real life”.

Roger Hargreaves began the Mr Men series when Adam asked him what a tickle looked like, and he drew a small orange man with long wiggly arms in response. Other than providing that inspiration, Adam Hargreaves was not involved in the series in any way until after his father died suddenly aged 53, after a stroke. The son of the author, who initially wanted to be a farmer, told the Telegraph in 2011 that he used to find his father’s bestselling series “embarrassing” and “a bit cliched”.

However, since creating his own new characters and books (while signing the covers in his father’s signature), Hargreaves said he had gained “a real respect” for what his father did and learned to love being part of his family’s legacy.

“It’s always fun creating new characters to add to the series,” he said, although he admitted that he had “a way to go” if he were to catch up with his father: Roger published a total of 60 books in the “classic collection” of Mr Men and Little Miss books (excluding seasonal titles or spin-offs), while Mr Fib and Little Miss Surprise will mark Adam’s 15th and 16th additions.

In April 2004, Roger Hargreaves’s widow, Christine, sold the rights to the Mr Men characters to the UK entertainment group Chorion for £28m. In December 2011, Chorion sold the brand to the Japanese company Sanrio. Adam Hargreaves remains the public face of the franchise, and was responsible for novelty characters such as Little Miss Stella, commissioned by Stella McCartney for the invitations to her 2006 fashion show, and Little Miss Princess, published in 2011 to coincide with the wedding of Prince William and Kate Middleton.

The Mr Men and Little Miss series now features more than 90 characters, and more than 250m books have been sold worldwide, in 17 different languages and 28 countries. The Little Miss books came under fire in 2018 when an undergraduate study on gender and stereotyping in children’s books showed that female characters in the books “were more passive, had less direct speech and relied on being saved more than male characters”.

Mr Fib and Little Miss Surprise will be published in the UK by Farshore, a division of HarperCollins, on 12 September 2024. The new characters come after Mr Calm and Little Miss Brave, which were introduced in 2021.