Theodor Seuss Geisel (2 March 1904 – 24 September 1991), better known by his pen name Dr. Seuss, was an American author and illustrator whose whimsical stories and imaginative characters made him one of the most beloved children’s writers of the 20th century. Over his career, he wrote and illustrated more than 60 books, which have sold over 600 million copies and been translated into multiple languages.

Born in Springfield, Massachusetts, Geisel attended Dartmouth College and later studied at the University of Oxford, though he left before earning a degree. His career began in advertising and political cartoons before he published his first children’s book, And to Think That I Saw It on Mulberry Street (1937). His works—such as The Cat in the Hat (1957), Green Eggs and Ham (1960), and How the Grinch Stole Christmas! (1957)—are known for playful rhymes, inventive vocabulary, and moral themes.

Geisel’s books have been adapted into animated specials, feature films, and stage productions, cementing his influence on generations of young readers. He received two Academy Awards, two Emmy Awards, a Pulitzer Prize, and numerous other honors. Dr. Seuss passed away in 1991, leaving behind a timeless literary legacy.