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
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.
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.
The Ottoman Turks actually conquered the whole of what was left of the Byzantine Empire in their days: its territories in northwestern Turkey and in southeastern Europe. They bought this empire to an end. The purpose of these conquests were power and wealth, which were the main aims of the Ottoman dynasty.
The Ottoman Empire expanded by conquering territory from neighboring states. In some cases, such as the Byzantine Empire (and all of its Despotates), the Sultante of Rum, the Empire of Trebizond, the Mamluk Sultanate of Egypt, and several Balkans States, were entirely consumeed by the Ottoman Empire. Others such as the Hungarian Empire and Romania were not entirely conquered but lost some lands.