A. A. Milne is the author who wrote the first Winnie the Pooh book, "Winnie-the-Pooh." It was published in 1926, and later followed by "The House at Pooh Corner" in 1928. These books introduced the world to the endearing characters of the series, such as Winnie the Pooh, Tigger, Eeyore, Piglet, and more, who continue to be loved by both children and adults alike.