Romulus Augustulus
Flavius Romulus Augustus (c. AD 460 – after AD 476; possibly still alive as late as AD 507), known derisively and historiographically as Romulus Augustulus, was the Roman emperor who ruled the Western Roman Empire from 31 October 475 until 4 September 476. He is often described as the "last Western Roman emperor", though some historians consider this to be Julius Nepos. His deposition by Odoacer traditionally marks the end of the Roman Empire in the West, the end of Ancient Rome, and the beginning of the Middle Ages in Western Europe.
Holy Roman Emperor
From an autocracy in Carolingian times (AD 800–924) the title by the 13th century evolved into an elected monarchy chosen by the prince-electors.
Various royal houses of Europe, at different times, became "de-facto" hereditary holders of the title, notably the Ottonians (962–1024) and the Salians (1027–1125). Following the late medieval crisis of government, the Habsburgs kept possession of the title without interruption from 1440–1740. 
The final emperors were from the House of Lorraine (Habsburg-Lorraine), from 1765–1806.
The Holy Roman Empire was dissolved after the defeat at Austerlitz by emperor Francis II, who continued to rule as Austrian emperor.