How about countries that used to begin with O?

While Oman is the only present-day country beginning with O, there are a few nations and empires of the past that began with O. The most successful of these was the Ottoman Empire, which collapsed into Turkey after WWI, and once occupied most of the Mediterranean coastline. Also, the Ostrogoth Empire began as an Italian kingdom and expanded throughout much of Europe, but the empire was scarcely documented and believed to have disappeared by 600 AD. The Omani Empire once occupied a broad swath of Arabia and Africa, but today is limited to the nation of Oman on Arabia's southern coast. By this definition, most of the Middle East, Northern Africa and Southern Europe began with the letter 'O' at one stage.