The author and illustrator David McKee, who has died aged 87, created some of the most loved and admired children’s picture books of the past 40 years, including Mr Benn, King Rollo and Not Now, Bernard. He was best known for his stories about Elmer the Patchwork Elephant, who loves to play practical jokes and longs to fit in.

Inspired by the mascot of the Bordeaux zoo, McKee’s first story about Elmer was published in 1968. It was not immediately obvious that it would become such a huge success, but McKee added a second title, Elmer Again and Again (1975), and then gradually more over the years – there are now dozens of Elmer books, which have been translated into more than 60 languages, and lines of branded clothing and toys.

As Elmer’s popularity increased, McKee kept a firm grip on how the patchwork elephant could be adapted to other media. His unusual wish not to pursue the highest commercial gain, combined with his modesty and lack of pretension, ensured Elmer’s status as a “national treasure” never threatened to overshadow his other books. McKee continued to love writing about Elmer because he enjoyed the response he got to the elephant’s warm-hearted message of inclusivity. He also felt close to him as a character. He said: “I know him very well and I enjoy the stories he tells me. In terms of publishing he has snowballed but I have never felt that he has been taken away from me.”

From the start of his career McKee was experimental in his storytelling and in how he used his illustrations. In all of his books there were certain common strands: there was a seamless bond between the words and pictures; they were witty in a deeply satisfying way; and they had underlying values of kindness, equality and pacificism, which were quietly stated and never imposed.

The Elmer books had obvious child appeal. Other characters, including Mr Benn and King Rollo, although definitely adults, had exciting adventures and a certain kind of power that engaged children. The first Mr Benn story, Red Knight, was published in 1967, and its follow-ups became the basis of a BBC series, written and animated by McKee, that was broadcast in 1971-72 and frequently repeated over the years.

In each episode, Mr Benn, a bowler-hatted office worker living in a cosy but rather dull suburban setting, leaves his home in Festive Road, London (based on Festing Road, Putney, where McKee once lived), and visits a fancy-dress shop. He tries on a costume, leaves via a magic door and goes on a gentle adventure – usually with a moral – suggested by the costume. In settings such as forests or jungles, he meets all kinds of people and animals, real or imaginary, before returning to his own world at the close of the tale. King Rollo also inspired an animated series, and in 1979 McKee set up the company King Rollo Films. Elmer’s adventures were broadcast as part of the Anytime Tales series in 1991.

The son of Violet (nee Easton) and Richard McKee, David was born in Tavistock, Devon, and, after leaving Tavistock grammar school, studied at Plymouth College of Art, and then Hornsey College of Art in London. His early published work as a freelance illustrator consisted of humorous sketches for publications including Punch and the Reader’s Digest.

His career as a book illustrator was launched in 1964, with Bronto’s Wings and Two Can Toucan, published by a small, independent publishing company, Abelard-Schuman, that was willing to take risks. There McKee worked with Klaus Flugge, who championed his books. When Flugge set up Andersen Press in 1976 it was obvious that McKee would move with him. Becoming great friends, the two worked together for the rest of McKee’s career.

In all his books, McKee was on the side of the child, frequently providing subversive messages for them to find in the illustrations. He never talked down to children in his stories and never spelled out the point of them. Not Now, Bernard (1980), which tells of the consequences of parents being too busy to listen to their children, is one of the most dramatic picture books of all time and one that is most open to interpretation by the reader. Less challenging but equally powerful is Two Monsters (1985), the story of monsters living on different sides of a mountain who talk to each other but never meet until, after a fierce argument, they destroy the mountain and, for the first time, stand together and see the world in the same way.

In addition to his own books, McKee illustrated books by other authors, including several of Michael Bond’s Paddington Bear stories. He was surprisingly overlooked in terms of awards. Although a convivial companion, he was relatively shy and modest, and appears not to have felt slighted by this, but he was delighted to be presented with the BookTrust lifetime achievement award in 2020: “The shock is hard to get over, and … even though I still don’t really believe it, I’m accepting it anyway, with great pleasure.”

He had recently finished the latest Elmer title, Elmer and the Gift, which is due to be published in September.

He is survived by his partner, Bakhta, and by three children, Chuck, Brett and Chantal, from his marriage to Barbara Ennuss, which ended in divorce.

• David John McKee, author and illustrator, born 2 January 1935; died 6 April 2022