http://en.wikipedia.org/wiki/John_R._Neill wrote:
<<John Rea Neill (November 12, 1877 - September 13, 1943) was a magazine and children's book illustrator primarily known for illustrating more than forty stories set in the Land of Oz, including L. Frank Baum's, Ruth Plumly Thompson's, and three of his own. His pen-and-ink drawings have become identified almost exclusively with the Oz series.
Born in Philadelphia, Pennsylvania, John R. Neill did his first illustration work for the Philadelphia's Central High School newspaper in 1894-95. Neill dropped out of school after one semester because he said, "they have nothing to teach me".
He then turned to advertising art for the Wanamaker department store in Philadelphia. He was first commissioned to illustrate The Marvelous Land of Oz, the second Oz book L. Frank Baum wrote, published in 1904.
Originally, Neill's illustrations were slightly reminiscent of Denslow's to bring continuity and familiarity to the characters, although Neill's work in this period was far more reminiscent of the work of his contemporary and friend, illustrator Joseph Clement Coll. Denslow's illustrations had been quite popular. However, as the series expanded, Neill brought his own unique flair to the illustrations, showing more artistic representations of the characters as well as beautiful paintings of numerous scenes. In fact, he was later named the Imperial Illustrator of Oz.
Dorothy drawn by Denslow appeared to be a chubby five- or six-year-old with long brown hair in two braids. Neill chose to illustrate a new Dorothy in 1907 when the character was reintroduced in Ozma of Oz. He illustrated the young girl in a more fashionable appearance. She is shown to be about ten years old, dressed in contemporary American fashions, with blonde hair cut in a fashionable bob. A similar modernization was given other female characters.
Neill continued to illustrate the Oz books after Baum's death, and his artwork was praised for helping give Ruth Plumly Thompson's books "legitimacy" in the eyes of Baum's fans. Neill would eventually succeed Thompson as the designated "Oz historian" and write several books himself.
Neill's illustrations were published in the leading magazines of the first few decades of the twentieth century, including Collier's, Vanity Fair, The Saturday Evening Post, The Ladies Home Journal, Century, Pictorial Review, The Delineator, Boys' Life, St. Nicholas, The People's Home Journal, and many others. In 1930 and 1931, he contributed a great deal of artwork to Argosy.
The Oz books he wrote for the firm of Reilly & Lee are considered part of the Famous Forty, and appeared one a year from 1940 to 1942. These were The Wonder City of Oz, The Scalawagons of Oz, and Lucky Bucky in Oz. He had completed a draft of The Runaway in Oz shortly before his death, but had not illustrated it, although a suite of sketches survives, as well as several rough drawings for the front cover. Reilly & Lee decided not to publish the manuscript, and it lay untouched until 1995, when it was published by Books of Wonder, edited and with illustrations by Eric Shanower.>>