King of the Romans (Latin: Rex Romanorum; German: König der Römer) was the title used by the king of East Francia following his election by the princes from the reign of Henry II (1002–1024) onward.
The title originally referred to any German king between his election and royal coronation until he was crowned Holy Roman Emperor by the Pope. The title was also used to designate the successor to the throne elected during the lifetime of a sitting Emperor. From the 16th century onwards, as German kings adopted the title of Emperor-elect and ceased to be crowned by the Pope, the title continued to be used solely for an elected successor to the throne during his predecessor's lifetime.
The actual title varied over time. During the Ottonian period, it was King of the Franks (German: König der Franken, Latin: Rex Francorum), from the late Salian period it was King of the Romans (German: König der Römer, Lat.: Rex Romanorum). In the Modern Period, the title King in Germania (German: König in Germanien, Lat.: Germaniae Rex) came into use. Finally, modern German historiography established the term Roman-German King (Römisch-deutscher König) to differentiate it both from the classical Roman Emperor as well as from the modern German Emperor.