(1904–91) US writer and illustrator; known as Dr. Seuss ; full name Theodor Seuss Geisel. His numerous children's books include And to Think That I Saw It on Mulberry Street (1937), Horton Hatches the Egg (1940), The Cat in the Hat (1957), Green Eggs and Ham (1960), and Oh, the Places You'll Go! (1990). For adults he wrote You're Only Old Once! (1986).