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.
Kaiser
The Holy Roman Emperors (962–1806) called themselves "Kaiser", combining the imperial title with that of "King of the Romans" (assumed by the designated heir before the imperial coronation); they saw their rule as a continuation of that of the Roman Emperors and used the title derived from the title "Caesar" to reflect their supposed heritage.
In 1806 the Holy Roman Empire was dissolved, but the title of Kaiser was retained by the House of Habsburg, the head of which, beginning in 1804, bore the title of Emperor (Kaiser) of Austria. After 1438, the Habsburgs had provided most of Holy Roman Emperors, so they saw themselves as legitimate heirs to the title they adopted. Despite Habsburg ambitions however, the Austrian Empire could no longer claim to rule over most of Germany, although they did rule over large areas of lands inhabited by non-Germans in addition to Austria. There were four Kaisers of the Austrian Empire who all belonged to the Habsburg dynasty.