Seuss, Dr., pseud. of Theodor Seuss Geisel, 1904-91, American author and illustrator of children's books, b. Springfield, Mass. His books are known for their blend of whimsy, zany humor, catchy verse, and outlandish illustrations. His style is evidenced in such books as Horton Hears a Who (1954), The Cat in the Hat (1957), Green Eggs and Ham (1960), and Oh, the Places You'll Go! (1990). In 1986 he published You're Only Old Once, about growing old. Although some early critics objected to his carefree style and sometimes violent illustrations, his books are immensely popular.