King of the Romans
A prospective Emperor first had to be elected King of the Romans (Latin: "Rex Romanorum"; German: "römischer König"). German kings had been elected since the 9th century; at that point they were chosen by the leaders of the five most important tribes (the Salian Franks of Lorraine, Ripuarian Franks of Franconia, Saxons, Bavarians, and Swabians). In the Holy Roman Empire, the main dukes and bishops of the kingdom elected the King of the Romans.