Roman emperor
Monarchical
The Roman emperor was the ruler and monarchical head of state of the Roman Empire, starting with the granting of the title augustus to Octavian in 27 BC. The term "emperor" is a modern convention, and did not exist as such during the Empire. Wikipedia
Past holders: Augustus, Nero Claudius Caesar Augustus Germanicus, Caligula, and more
First monarch: Augustus
Last monarch: Theodosius I (unified); Julius Nepos (Western); Constantine XI (Eastern)