The following are the modern day countries of which all of their territory (except sparsely populated regions) was controlled by the Ottoman Empire at some point:
spain
Muslin armies gain control of Eastern Europe during the time of the Ottoman Empire. The areas of Bulgaria, Romania and Yugoslavia were under the control of the automatic Empire.
Russia tried to gain control but was only partially successful. Territories such as modern Armenia and Azerbaijan were once Ottoman but were lost to Russia. Much of the Balkans fought for independence from the Ottomans but didn't become Russian.
Ottoman Empire
The two primary areas that sought to gain control over the Balkan region were the Austro-Hungarian Empire and the Ottoman Empire. The Austro-Hungarian Empire aimed to expand its influence and secure its borders against rising nationalism, while the Ottoman Empire sought to maintain its declining control over its territories in the Balkans. This competition contributed to tensions that ultimately played a significant role in the outbreak of World War I.
serbia
Control of these two straights would give them access to the Mediterranean sea. (for trade)
Arabs in the region wanted to gain independence from the Turkish leaders of the Ottoman Empire.
Russia's interest in conquering the Ottoman Empire historically stemmed from a desire to expand its territory, enhance its influence in the Balkans, and gain access to warm-water ports for trade and military purposes. The Ottoman Empire's decline presented an opportunity for Russia to assert its dominance in southeastern Europe and the Black Sea region. Additionally, Russia sought to protect and promote Orthodox Christianity in areas under Ottoman control, aligning with its broader geopolitical and cultural objectives. Ultimately, conquering the Ottoman Empire would have strengthened Russia's position as a major power in Eurasia.
North Yemen became independent from the Ottoman Empire in 1918.
Greek worked with the Great Powers of Europe and fought for their independence from the Ottoman Empire.
The independence of the modern Romania is from 9 May 1877, after the war against Ottoman Empire.