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.
Theodosius I
Theodosius I (; ; 11 January 347 – 17 January 395), also known as Theodosius the Great, was a Roman Emperor from 379 to 395, and the last emperor to rule over both the Eastern and the Western halves of the Roman Empire. On accepting his elevation, he campaigned against Goths and other barbarians who had invaded the Empire. His resources were not sufficient to destroy them or drive them out, which had been Roman policy for centuries in dealing with invaders. By treaty, which followed his indecisive victory at the end of the Gothic War, they were established as "foederati", autonomous allies of the Empire, south of the Danube, in Illyricum, within the Empire's borders. They were given lands and allowed to remain under their own leaders, a grave departure from Roman hegemonic ways. This turn away from traditional policies was accommodationist and had grave consequences for the Western Empire from the beginning of the century, as the Romans found themselves with the impossible task of defending the borders and deal with unruly federates within. Justinian I (527-565), intent upon recovering lost regions, reversed the policy with the conquest of North Africa and Italy. Theodosius I was obliged to fight two destructive civil wars, successively defeating the usurpers Magnus Maximus in 387-388 and Eugenius 394, not without material cost to the power of the Empire.