Wanda Hazel Gág (pronounced GOG) was an American author and illustrator. She was born on March 11, 1893, in New Ulm, Minnesota. Her mother, Elisabeth Biebl, and father, Anton, were of Bohemian descent. Both parents were artists who had met in Germany. They had seven children, who all acquired some level of artistic talent. Gág grew up the eldest of these, and despite their economic hardships, the family was surrounded by music, art, light, and love, making it for the most part a joyous existence.

When Gág was 15, her father died of tuberculosis; his final words to her were: "Was der Papa nicht thun konnt', muss die Wanda halt fertig machen." ("What Papa couldn't do, Wanda will have to finish.") Following Anton's death the family was on welfare, and some townspeople thought that Gág should quit high school and get a steady job to help support her family. Despite this pressure, Gág continued her studies. After graduating in 1912, she taught country school in Springfield, Minnesota, from November 1912 to June 1913.

In 1917, she illustrated A Child’s Book of Folk-Lore, following which she worked on many different projects and became a well-known artist and author. Her art exhibition in the New York Public Library in 1923 was the true beginning of her fame. She gained a reputation as an illustrator for socialist publications such as The New Masses, and she considered herself a feminist and advocate of free love in the 1920s. She did not marry her lover until later in life, for instance, although she lived with him before they wed.

She was especially esteemed for her lithographs, though today if her name is known at all it is usually from her children's books, specifically the classic Millions of Cats, which won the Lewis Carroll Shelf Award in 1958. Gág also received the Newbury Honor Award for this book, and the combined effects of it and her exhibition gave her the funds she needed to carry on her work without stress.

She died in New York City on June 27, 1946.