Eric Carle, the man behind children's' book The Very Hungry Caterpillar, has died at the age of 91, his family has said.
His family said that the author and illustrator died on Sunday at his home in Northampton, Massachusetts.
Carle is best known for his children's book The Very Hungry Caterpillar, which was published in 1969, which told the story of a caterpillar's metamorphosis into a beautiful butterfly.
It sold more than 40 million copies around the world, was translated into 60 languages and gave way to stage shows and cuddly toys.
Mr Carle told The New York Times in 1994: "I remember that as a child, I always felt I would never grow up and be big and articulate and intelligent.
"Caterpillar is a book of hope: you, too, can grow up and grow wings."
Paying her own tribute on Twitter, former first lady Michelle Obama said: "His work has been read (and re-read, and re-read) tens of millions of times over the years, one generation's gift to the next.
"Thank you Eric Carle for filling our lives with so much wonder and joy."
The author penned more than 75 books throughout his career, some with other writers - but they were mostly solo ventures.
His more recent work included the 2015 book The Nonsense Show, which was centred around flying fish, cat-taming mice and animals in the circus.
Themes explored by Carle often included children mastering the world, animals in predicaments and the love of family.
In 2002, he and his late wife Barbara, founded the Eric Carle Museum Of Picture Book Art, in Ameherst, Massachusetts, which serves as a home for illustrations from picture books from around the world.
He is survived by a son and a daughter.