which of the major planets of our solar system is named for a greek god, not roman?

The only major planet in our solar system named for a Greek god rather than a Roman one is Uranus. All the other classical planets use Roman names (for example, Jupiter instead of Zeus, Venus instead of Aphrodite, Neptune instead of Poseidon), but Uranus keeps the Greek name of the sky god rather than the equivalent Roman name, Caelus.