William Erwin Eisner (/ˈaɪznər/ EYEZ-nər; March 6, 1917 – January 3, 2005) was an American cartoonist, writer, and entrepreneur. He was one of the earliest cartoonists to work in the American comic book industry, and his series The Spirit (1940–1952) was noted for its experiments in content and form. In 1978, he popularized the term "graphic novel" with the publication of his book A Contract with God. He was an early contributor to formal comics studies with his book Comics and Sequential Art (1985). The Eisner Award was named in his honor and is given to recognize achievements each year in the comics medium; he was one of the three inaugural inductees to the Will Eisner Comic Book Hall of Fame.

Eisner's father, Shmuel "Samuel" Eisner, was born to Galician Jewish parents on March 6, 1886, in Kolomyia, Austria-Hungary (present-day Ukraine), and was one of eleven children. He aspired to be an artist, and as a teenager painted murals for rich patrons and Catholic churches in Vienna. To avoid conscription in the army, he moved to New York before the outbreak of World War I. There he found getting work difficult, as his English skills were poor. He made what living he could painting backdrops for vaudeville and the Jewish theater.

Eisner's mother, Fannie Ingber, was born to Romanian Jewish parents on April 25, 1891, on a ship bound for the US. Her mother died on her tenth birthday and was quickly followed by her father. An older stepsister thereafter raised her and kept her so busy with chores that she had little time for socializing or schooling; she did what she could later in life to keep knowledge of her illiteracy from her children.

Shmuel and Fannie, who were distant relatives, met through family members. They had three children: son Will Erwin, born on his father's birthday in 1917; son Julian, born February 3, 1921; and daughter Rhoda, born November 2, 1929.

Eisner was born in Brooklyn. He grew up poor, and the family moved frequently. Young Eisner often got into physical confrontations when subjected to antisemitism from his schoolmates.

Young Eisner was tall and of sturdy build, but lacked athletic skills. He was a voracious consumer of pulp magazines and film, including avant-garde films such as those by Man Ray. To his mother's disappointment, Eisner had his father's interest in art, and his father encouraged him by buying him art supplies.

Eisner's mother frequently berated his father for not providing the family a better income, as he went from one job to another. Without success he also tried his hand at such ventures as a furniture retailer and a coat factory. The family situation was especially dire following the Wall Street crash of 1929 that marked the beginning of the Great Depression. In 1930, the situation was so desperate that Eisner's mother demanded that he, at thirteen, find some way to contribute to the family's income. He entered working life selling newspapers on street corners, a competitive job where the toughest boys fought for the best locations.

Eisner attended DeWitt Clinton High School. With influences that included the early 20th-century commercial artist J. C. Leyendecker, he drew for the school newspaper (The Clinton News), the literary magazine (The Magpie) and the yearbook (The Clintonian) and did stage design, leading him to consider doing that kind of work for theater. Upon graduation, he studied under Canadian artist George Brandt Bridgman for a year at the Art Students League of New York. Contacts made there led to a position as an advertising writer-cartoonist for the New York American newspaper. Eisner also drew $10-a-page illustrations for pulp magazines, including Western Sheriffs and Outlaws.