The Mr Men are celebrating their 35th anniversary with an exhibition at London's Animation Art Gallery.
The first character to be created was Mr Tickle, when artist Roger Hargreaves' son Adam asked his father: "What does a tickle look like?"
There are now more than 40 Mr Men characters and 30 Little Miss books.
Little Miss Sunshine was among the first of the Little Miss books to be created by Roger Hargreaves, starting in 1981.
Following Roger Hargreaves' death in 1988, his son Adam took over the pen to create new characters.
Roger Hargreaves has been named the third best-selling children's author after JK Rowling and Jacqueline Wilson, selling more than 100 million copies worldwide.
The exhibition, which has now opened to the public, features original etchings of characters including Mr Bump, alongside the history of the Mr Men.
The Mr Men and Little Misses had their own TV series, with Arthur Lowe narrating the Mr Men and Pauline Collins and John Alderton narrating The Little Miss series.
To celebrate the anniversary Adam Hargreaves has created two new characters - Mr Birthday, who loves parties, and Little Miss Birthday, who loves presents.