Ivan Sratsimir or Ivan Stratsimir (Bulgarian: Иван Срацимир) was emperor (tsar) of Bulgaria in Vidin from 1356 to 1396. He was born in 1324 or 1325, and he died in or after 1397. Despite being the eldest surviving son of Ivan Alexander, Ivan Sratsimir was disinherited in favour of his half-brother Ivan Shishman and proclaimed himself emperor in Vidin. When the Hungarians attacked and occupied his domains, he received assistance from his father and the invaders were driven away.

After the death of Ivan Alexander in 1371 Ivan Sratsimir broke off ties with Tarnovo and even placed the archbishop of Vidin under the jurisdiction of the Patriarchate of Constantinople to demonstrate his independence. Due to its geographical position, Vidin was initially safe from attacks by the Ottoman Turks who were ravaging the Balkans to the south and Ivan Sratsimir made no attempts to assist Ivan Shishman in his struggle against the Ottomans. Only after the fall of Tarnovo in 1393 did his policy become more active and he eventually joined the crusade of the Hungarian king Sigismund. However, after the disastrous battle of Nicopolis in 1396, the Ottomans marched to Vidin and seized it. Ivan Sratsimir was captured and imprisoned in Bursa where he was probably strangled. Although his son Constantine II claimed the title Emperor of Bulgaria and at times controlled some parts of his father's realm, Ivan Sratsimir is generally regarded by historians as the last ruler of medieval Bulgaria.

Sratsimir Hill on Trinity Peninsula in Antarctica is named after him.

Bulgaria (Bulgarian: България, tr. Bǎlgariya), officially the Republic of Bulgaria (Bulgarian: Република България, tr. Republika Bǎlgariya, IPA: [rɛˈpublikɐ bɐɫˈɡarijɐ]), is a country in southeastern Europe. It is bordered by Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, and the Black Sea to the east. With a territory of 110,994 square kilometres (42,855 sq mi), Bulgaria is Europe's 16th-largest country.

Organised prehistoric cultures began developing on current Bulgarian lands during the Neolithic period. Its ancient history saw the presence of the Thracians, Ancient Greeks, Persians, Celts, Romans, Goths, Alans and Huns. The emergence of a unified Bulgarian state dates back to the establishment of the First Bulgarian Empire in 681 AD, which dominated most of the Balkans and functioned as a cultural hub for Slavs during the Middle Ages. With the downfall of the Second Bulgarian Empire in 1396, its territories came under Ottoman rule for nearly five centuries. The Russo-Turkish War of 1877-78 led to the formation of the Third Bulgarian State. The following years saw several conflicts with its neighbours, which prompted Bulgaria to align with Germany in both world wars. In 1946 it became a one-party socialist state as part of the Soviet-led Eastern Bloc. In December 1989 the ruling Communist Party allowed multi-party elections, which subsequently led to Bulgaria's transition into a democracy and a market-based economy.

Bulgaria's population of 7.2 million people is predominantly urbanised and mainly concentrated in the administrative centres of its 28 provinces. Most commercial and cultural activities are centred on the capital and largest city, Sofia. The strongest sectors of the economy are heavy industry, power engineering, and agriculture, all of which rely on local natural resources.

The country's current political structure dates to the adoption of a democratic constitution in 1991. Bulgaria is a unitary parliamentary republic with a high degree of political, administrative, and economic centralisation. It is a member of the European Union, NATO, and the Council of Europe; a founding state of the Organization for Security and Co-operation in Europe (OSCE); and has taken a seat at the UN Security Council three times.