Theodor Seuss Geisel was born in Springfield, Massachusetts to German-American parents. He attended public schools and then went to Dartmouth College, where he became editor of the Dartmouth Jack-O-Lantern. When he was barred from all extracurricular activities, he continued to write for the paper using the pseudonym "Seuss." After he graduated, he became a contributor to the magazine The Judge, and began to sign his work as "Dr. Seuss."

He attended Lincoln College, Oxford to earn a D.Phil in literature but married Helen Palmer in 1927 and returned to the United States without earning the degree. He published humorous articles and illustrations in The Judge, The Saturday Evening Post, Life, Vanity Fair, and Liberty, supporting himself and his wife through the Great Depression with commercial illustrations for companies like General Electric, NBC, and Standard Oil. He also created a short-lived comic strip called Hejji in 1935.

In 1937, after returning from an ocean voyage to Europe, he wrote his first book, And to Think That I Saw It on Mulberry Street. During World War II, he created political cartoons and worked as an editorial cartoonist for the left-wing New York City newspaper, PM. His political cartoons were later published in Dr. Seuss Goes to War. In 1942, he produced propaganda posters for the Treasury Department and the War Production Board and joined the Animation Department of the First Motion Picture Unit of the U.S. Army Air Forces in 1943.

After the war, he moved with his wife to La Jolla, California and returned to writing and illustrating children's books. In 1954, Life magazine published an article on the dullness of children's books, inspiring Geisel to write The Cat in the Hat. In 1967, his wife Helen committed suicide, and he married Audrey Stone Dimond in 1968. Geisel passed away in La Jolla, California in 1991.

Throughout his career, Geisel wrote over 60 children's books, using the pseudonyms "Dr. Seuss," "Theo. LeSieg," and "Rosetta Stone." His works include popular titles such as If I Ran the Zoo (1950), Horton Hears a Who! (1954), The Cat in the Hat (1957), How the Grinch Stole Christmas! (1957), Green Eggs and Ham (1960), One Fish, Two Fish, Red Fish, Blue Fish (1960), The Sneetches and Other Stories (1961), The Lorax (1971), The Butter Battle Book (1984), and Oh, the Places You'll Go! (1990). His books have sold over 600 million copies worldwide and have been translated into more than 20 languages.

Geisel received numerous accolades, including two Primetime Emmy Awards for Outstanding Children's Special and Outstanding Animated Program, and a Pulitzer Prize Special Citation in 1984. His birthday, March 2, is celebrated as National Read Across America Day.