Countries That Start With O: Complete List & Guide

There is only 1 sovereign country that starts with the letter O: Oman. The Sultanate of Oman is a nation on the southeastern coast of the Arabian Peninsula in Western Asia, bordered by the United Arab Emirates, Saudi Arabia, and Yemen. While Oman is the sole UN-recognized country beginning with O, several notable territories, dependencies, and historical regions also share this initial letter.

This is a complete guide to countries and territories that start with the letter O, with an in-depth look at Oman — one of the oldest independent states in the Arab world.

Complete List of Countries Starting With O

• Oman — Sultanate of Oman (sovereign nation, UN member)

Oman: The Sultanate on the Arabian Peninsula

Oman (officially the Sultanate of Oman) occupies a strategic position at the southeastern corner of the Arabian Peninsula, controlling the southern shore of the Strait of Hormuz — one of the world's most critical oil shipping chokepoints. With an area of 309,500 square kilometers (roughly the size of Italy or New Mexico), Oman is the third-largest country on the Arabian Peninsula after Saudi Arabia and Yemen.

• Capital: Muscat
• Area: 309,500 km²
• Population: ~5.1 million (2026 est.)
• Language: Arabic (official); English widely spoken
• Religion: Islam (predominantly Ibadi, a distinct branch found almost exclusively in Oman)
• Government: Absolute monarchy (Sultanate)
• Currency: Omani Rial (OMR) — one of the world's highest-valued currencies

Oman has a remarkably diverse geography for its size. The Al Hajar Mountains run along the northern coast, with Jebel Shams ("Mountain of the Sun") reaching 3,009 meters — the highest point in the eastern Arabian Peninsula. The vast Rub al Khali (Empty Quarter) desert extends into Oman's western interior, while the Dhofar region in the south receives monsoon rains (the khareef) from June to September, creating a lush green landscape unlike anywhere else on the Arabian Peninsula.

The country's coastline stretches over 3,165 kilometers along the Arabian Sea, the Gulf of Oman, and the Persian Gulf. This extensive coast has made Oman a maritime power for centuries. Omani sailors and traders established connections with East Africa, India, and China long before European exploration. The Omani Empire once controlled Zanzibar, parts of the East African coast, and territories as far as modern-day Pakistan.

Oman's History and Heritage

Oman is one of the oldest continuously inhabited regions in the Arabian Peninsula. Archaeological evidence shows human settlement dating back at least 100,000 years. The ancient land of Magan, mentioned in Sumerian texts as a source of copper, is believed to have been located in what is now Oman. The country embraced Islam in the 7th century during the lifetime of the Prophet Muhammad, and the Ibadi school of Islam — distinct from both Sunni and Shia traditions — became dominant and remains so today.

Modern Oman was transformed by Sultan Qaboos bin Said, who took power in 1970 and embarked on a dramatic modernization program. When he came to power, Oman had only three schools, one hospital, and 10 kilometers of paved road. By the time of his death in 2020, Oman had world-class infrastructure, a diversified economy, and high human development indicators. Sultan Haitham bin Tariq succeeded him and has continued the modernization agenda, particularly the Vision 2040 economic diversification plan.

Territories and Regions Starting With O

While Oman is the only sovereign country starting with O, several other notable places share this initial letter:

• Oceania: Not a country, but the geographic region encompassing Australia, New Zealand, Melanesia, Micronesia, and Polynesia — sometimes referred to in geographic contexts
• Okinawa: A prefecture of Japan, historically the independent Ryukyu Kingdom, known for US military bases and exceptional longevity among residents
• Ontario: Canada's most populous province, home to Ottawa (the capital) and Toronto
• Oregon: A US state known for its diverse geography from Pacific coastline to Cascade volcanoes
• Orkney Islands: A Scottish archipelago north of mainland Britain with Viking heritage

Why Only One Country Starts With O

The letter O is one of the rarest starting letters for country names. Only Oman begins with O among the 195 internationally recognized countries. This is comparable to the letter Q (which begins only Qatar) and the letter Y (only Yemen). By contrast, the letter S begins the most country names with 26 countries, followed by C with 17. The distribution of starting letters reflects the diverse linguistic origins of country names — Oman's name derives from the Arabic "Uman," possibly related to the historical figure Oman bin Ibrahim al-Khalil or to the Arabic word for "settled people."

Key Facts

• There is 1 country that starts with the letter O: Oman.
• Oman controls the southern shore of the Strait of Hormuz, through which roughly 20% of the world's oil passes.
• The Omani Rial is one of the highest-valued currencies in the world (1 OMR ≈ 2.60 USD).
• Oman practices Ibadi Islam, a distinct branch found almost exclusively in Oman and parts of East Africa.
• The letter S starts the most country names with 26 countries, while O, Q, and Y each start only one.

Fun Facts

• Oman's frankincense trail is a UNESCO World Heritage Site — the resin was once more valuable than gold in the ancient world.
• The Omani Empire once ruled Zanzibar, and the Sultan of Oman moved his capital there in 1840, making it one of history's most unusual colonial arrangements.
• Oman's Wahiba Sands desert contains sand dunes over 100 meters tall and has been used by NASA as a Mars terrain analog.
• The letters W and X do not begin any sovereign country name at all, making O still better represented than some letters.