Who wrote the 'Wizard of Oz' series?

L. Frank Baum wrote the Wizard of Oz series. His first Oz book, The Wonderful Wizard of Oz, was published in 1900 and introduced Dorothy, the Scarecrow, the Tin Woodman, the Cowardly Lion, and the magical Land of Oz.

Baum followed it with thirteen more Oz novels, including The Marvelous Land of Oz, Ozma of Oz, and The Emerald City of Oz. He died in 1919, but Glinda of Oz appeared posthumously in 1920. Later Oz books were written by authors such as Ruth Plumly Thompson, who continued the series under the publisher's direction.

A common mix-up is the title: the original book is The Wonderful Wizard of Oz, while The Wizard of Oz became the more familiar title through stage, film, and later editions. Baum also worked with illustrator W. W. Denslow, whose artwork helped define the original book's visual identity.