Theodor Seuss Geisel, known as Dr. Seuss, was an American children's author, political cartoonist, illustrator, and filmmaker. He published over 60 books, which have sold more than 600 million copies worldwide. His Piscean imagination created whimsical worlds filled with fantastical creatures and profound life lessons, making him one of the most beloved children's authors in history. His works like "The Cat in the Hat" and "Green Eggs and Ham" revolutionized children's literature.