Francis II, Holy Roman Emperor
Francis II (; 12 February 1768 – 2 March 1835) was the last Holy Roman Emperor, ruling from 1792 until 6 August 1806, when he dissolved the Holy Roman Empire of the German Nation after the decisive defeat at the hands of the First French Empire led by Napoleon at the Battle of Austerlitz. In 1804, he had founded the Austrian Empire and became Francis I, the first Emperor of Austria, ruling from 1804 to 1835, so later he was named the one and only "Doppelkaiser" (double emperor) in history.
For the two years between 1804 and 1806, Francis used the title and style "by the Grace of God elected Roman Emperor, ever Augustus, hereditary Emperor of Austria" and he was called the "Emperor of both the Holy Roman Empire and Austria". He was also Apostolic King of Hungary and Bohemia as Francis I. He also served as the first president of the German Confederation following its establishment in 1815.
Roman emperor
Due to the cultural rupture of the Turkish conquest, most western historians treat Constantine XI as the last meaningful claimant to the title Roman Emperor. From 1453, one of the titles used by the Ottoman Sultans was "Caesar of Rome" (Turkish: "Kayser-i Rum"), part of their titles until the Ottoman Empire ended in 1922. A Byzantine group of claimant Roman emperors existed in the Empire of Trebizond until its conquest by the Ottomans in 1461, though they had used a modified title since 1282.