The Answer

Good votes, people. Anne was the closest, with "Shakespeare," and I love the variety, from "Dr. Seuss" to "Plato," but the answer is ... Agatha Christie.
Tim points out that the "number of translations" means number of works written times number of languages translated into. Since Ms. Christie wrote approximately 42 billion mystery novels, assuming each of them was translated into at least one other language, she got the edge on Shakespeare et al.