American artist and author whose dynamic visual style imbued the often commonplace subjects of both her serious art and her illustrated books for children with an intense vitality.

Gág was the daughter of a Bohemian immigrant artist. While attending high school in Minnesota, she helped support her family by contributing drawings to a children's supplement to the Minneapolis Journal. She attended the St. Paul Art School on a scholarship, and from 1915 to 1917 she studied at the Minneapolis School of Art. In 1917 she traveled to New York City and entered the Art Students League, where she studied with John Sloan (Sloan, John French) and other noted teachers.

A show of Gág's drawings, lithographs, and woodcuts at the Weyhe Gallery in New York in 1926 brought her first recognition as a serious artist, and subsequent shows there in 1928, 1930, and 1940 increased her reputation. She was represented in the Museum of Modern Art's 1939 exhibition “Art in Our Time,” which was presented at the time of the New York World's Fair. At the suggestion of a children's book editor, she wrote and illustrated Millions of Cats (1928), which became a classic children's book. Her subsequent books for children include The Funny Thing (1929), A.B.C. Bunny (1933), Gone Is Gone (1935), and Nothing at All (1941). She also translated and illustrated Tales from Grimm (1936), Snow White and the Seven Dwarfs (1938), Three Gay Tales from Grimm (1943), and More Tales from Grimm (1947). Growing Pains: Diaries and Drawings for the Years 1908–1917 (1940, reprinted 1984) is a memoir based on her journals.