Emperor
The first Austrian Emperor was the last Holy Roman Emperor Francis II. In the face of aggressions by Napoleon, Francis feared for the future of the Holy Roman Empire. He wished to maintain his and his family's Imperial status in the event that the Holy Roman Empire should be dissolved, as it indeed was in 1806 when an Austrian-led army suffered a humiliating defeat at the Battle of Austerlitz. After which, the victorious Napoleon proceeded to dismantle the old "Reich" by severing a good portion from the empire and turning it into a separate Confederation of the Rhine. With the size of his imperial realm significantly reduced, Francis II, "Holy Roman Emperor" became Francis I, "Emperor of Austria". The new imperial title may have sounded less prestigious than the old one, but Francis' dynasty continued to rule from Austria and a Habsburg monarch was still an emperor ("Kaiser"), and not just merely a king ("König"), in name.
Holy Roman Empire
After Charlemagne died in 814, the imperial crown passed to his son, Louis the Pious. Upon Louis' death in 840, it passed to his son Lothair, who had been his co-ruler. By this point the territory of Charlemagne had been divided into several territories, and over the course of the later ninth century the title of Emperor was disputed by the Carolingian rulers of Western Francia and Eastern Francia, with first the western king (Charles the Bald) and then the eastern (Charles the Fat), who briefly reunited the Empire, attaining the prize. After the death of Charles the Fat in 888, however, the Carolingian Empire broke apart, and was never restored. According to Regino of Prüm, the parts of the realm "spewed forth kinglets", and each part elected a kinglet "from its own bowels". After the death of Charles the Fat, those crowned emperor by the pope controlled only territories in Italy. The last such emperor was Berengar I of Italy, who died in 924.