Mr Rude and Mr Cool join Mr Men ensemble

For a set of new characters in one of the most successful children's book series, they sound alarmingly like the gangsters from Reservoir Dogs.

Mr Cool, Mr Rude and Mr Good are the new faces in the first revival of the Mr Men books, 15 years after the death of their creator, Roger Hargreaves.

They will be joined by Little Miss Bad, Little Miss Scary and Little Miss Whoops when the first new Mr Men books since Mr Hargreaves' death are published later this year.

The books have been written and drawn by Mr Hargreaves' son Adam, who was the inspiration for the original Mr Man in 1971, when he asked his father what a tickle looked like.

Mr Hargreaves responded by drawing a small round figure with ludicrously long arms and an insatiable urge to tickle, and over the decades Mr Tickle was followed by 42 strangely shaped personalities. They were originally all male, but were joined by a succession of Little Misses in the 1980s, under pressure from the author's daughters.

The popularity of the original characters led to a television series, sold 100 million books and created a business worth £130m, which Adam Hargreaves and his sister Amelia Beddoe took over when their father died from a stroke in 1988.

Ms Beddoe said yesterday they waited a long time before publishing because her brother did not feel comfortable stepping into his father's shoes."We have tried to keep the essence of the original stories, humorous and not too moralistic," she said.

"We'd always wanted a Mr Rude because it's such a good name. He can't be too rude because it's a children's book but he calls Mr Small 'titch' and Mr Nosey 'big nose' and he just ignores Mr Happy until he is forced to be nice to him. Mr Cool can do anything he wants. He appears in the bedroom of a little boy who is ill and takes him off on adventures that help him get better."

The three new male characters are joined by Little Miss Bad, Little Miss Scary and Little Miss Whoops in the books, to be released in April and September.

Ms Beddoe said nothing fundamental had changed. "They are aimed at three to seven-year-olds and three-year-olds are the same now as they were 30 years ago."