No, most have been illistrated by Josh Kirby.
A cat named Izzie
No, Sir Terry Pratchett and JK Rowling have not collaborated on any projects. They are both widely successful authors in their own right, known for their distinct writing styles and series.
they write and illustrate their own books
No, J.K. Rowling did not illustrate her own books. The illustrations for the Harry Potter series were done by various artists, with Mary GrandPré being the primary illustrator for the US editions.
No, I do not believe he illustrated any books, be they his own or someone other's
Most of them. There are very few authors who illustrate their own stories, and they're going to be the children's authors who write picture books.
In the Discworld series by Terry Pratchett, Foul Ole Ron is a character who has a form of mental illness and frequently repeats nonsensical phrases. "Millennium hand and shrimp" is one of his signature phrases that has no real meaning and is just part of his eccentric ramblings.
It is difficult to provide an exact percentage, as it varies greatly. Some writers both illustrate and write their own books, while others collaborate with separate illustrators. It may depend on the genre and type of book being created.
Dr. Seuss was the illustrator of most of his own books. If he did not illustrate the books, he wrote them under the pen name of Theo LeSeig. Theo was short for Theodore. LeSeig was his real last name backwards.
Roald Dahl did not illustrate his own books. His stories were illustrated by various artists, including Quentin Blake who is well known for his illustrations of Dahl's works.
No, the different books were illustrated by various people for the various countries. If you want to know the names, go to wikipedia and type in the individual book names. The illustrators for the US and UK editions are listed in the box on the right hand side.
Children can start creating their own books as soon as they are able to draw or write, typically around the ages of 4-6. At this stage, they begin to explore their creativity and storytelling abilities by combining images and words in simple ways to convey their ideas. Encouraging children to create their own books can help foster a love for reading and writing at an early age.