Plato's Final Letter is the last of Plato's works, written around the year 380 BC. It is a letter addressed to Dionysius II, the ruler of Syracuse, in which Plato discusses his views on politics and government. The term OMEGA is the last letter of the Greek alphabet, and is often used to symbolize the end or completion of something. Thus, OMEGA is an appropriate answer for Plato's Final Letter, as it signifies the end of Plato's works.