Historians typically give Charlemagne the credit for creating the Holy Roman Empire. We must note, however, that Charlemagne did not give this name to the empire that he created. The name was not applied to the empire until centuries after Charlemagne lived.
The Holy Roman Empire is said to have originated when Pope Leo III crowned Charlemagne. This happened in 800 CE. When the pope did this, he was officially giving sanction to Charlemagne’s rule. This is why the empire is called “holy.” It is called “Roman” because it was seen as a successor to the old Roman Empire. It was the first empire to dominate a large area of Europe after the fall of the Western Roman Empire.