Holy Roman Emperor - AbsoluteAstronomy.com

The Holy Roman Emperor is a term used by historians to denote a medieval

Middle Ages

The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

ruler who, as German King, had also received the title of "Emperor of the Romans

Roman Emperor

The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

" from the Pope

Pope

The Pope is the Bishop of Rome, a position that makes him the leader of the worldwide Catholic Church . In the Catholic Church, the Pope is regarded as the successor of Saint Peter, the Apostle...

. After the 16th century, this elected monarch governed the Holy Roman Empire

Holy Roman Empire

The Holy Roman Empire was a realm that existed from 962 to 1806 in Central Europe.It was ruled by the Holy Roman Emperor. Its character changed during the Middle Ages and the Early Modern period, when the power of the emperor gradually weakened in favour of the princes...

(later called Holy Roman Empire of the German Nation), a Central European union of territories of the Medieval and Early Modern period.
The title of Emperor (Imperator
Imperator
The Latin word Imperator was originally a title roughly equivalent to commander under the Roman Republic. Later it became a part of the titulature of the Roman Emperors as part of their cognomen. The English word emperor derives from imperator via Old French Empreur...

) carried with it an important role as protector of the Catholic Church

Roman Catholic Church

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...