What if the Persians under the emperor Xerxes had conquered mainland Greece in 480–79 B.C. and added a new satrapy to the already hypertrophied Achaemenid Persian Empire, the biggest thing yet in the storied Near East? It would have been largely due, ultimately, to the “Great King,” the “King of Kings,” Emperor Cyrus II the Great. Many such counterfactuals come to mind as we contemplate the extraordinary career and afterlife reception of Cyrus, the founder in about 550 B.C. of an empire destined to continue (minus mainland Greece) for over two centuries before it fell victim at last to the ambitions of another “Great,” Alexander III of Macedon, in 330 B.C.