King of the Romans () was the title used by the elected ruler of the Holy Roman Empire, the Imperator futurus ("Emperor to-be"— and in today's terminology "Emperor-elect") prior to his imperial coronation performed by the Pope, (usually, but not always: many Holy Roman Emperors stayed "Emperor-elect" but were called Emperor despite never being anointed and crowned by the Pope). The title was later also used by the Emperor's heir-designate, who was elected during the lifetime of his predecessor. The title came into common use in the High Middle Ages in the 11th century, during the several decades (1056-1084) of the reign of Henry IV, Holy Roman Emperor (King Henry IV), in which he ruled the Empire but had not yet been crowned by the Pope.

Origin

The King of the Romans (Rex Romanorum) was the title of the ruler of the Holy Roman Empire, before he was crowned Emperor of the Romans by the Pope. The Holy Roman Empire included several kingdoms, including the Kingdom of Germany, Kingdom of Italy, Kingdom of Bohemia and Kingdom of Arles at different points of history.

Before the King of the Romans could be crowned, he first had to be elected by the German nobility as King of the Germans (Rex Teutonicorum). The elections had to be held in the county of Franken, and all German nobility present could vote. Later this procedure was simplified, and only seven Prince-electors had the right to vote. After being elected as King of the Germans, he could be crowned King of the Germans in Aachen, by an archbishop. The final step to become Emperor of the Romans was to travel to Rome and be crowned Emperor by the pope. Not all Kings of the Romans made this step, sometimes because of hostile relations to the current pope.

The title Rex Romanorum was used occasionally by the Ottonian rulers and especially by Emperor Henry II to highlight the Roman nature of their Empire, which was contested by the Byzantine Emperors.
Rex Romanorum became the standard title under the Salian King Henry IV during the Investiture Controversy. Pope Gregory VII insisted on using the title Rex Teutonicorum to counter Henry's imperial claims. As King, Henry was the Imperator futurus but at that point he had not been crowned Emperor. In reaction to Gregory's usage, Henry made Rex Romanorum his standard title until he was crowned Emperor in 1084.

Henry's successors imitated this practice, being called Rex Romanorum before and Imperator Romanorum after their Roman coronation.

List of ruling Kings of the Romans

The following were Kings of the Romans who ruled or claimed to rule the Empire without subordination to another ruler, but who had not been crowned Emperor or claimed the title without coronation. See also List of German monarchs.
House of Saxony (Liudolfings)

• Otto III, 983-996 (crowned Emperor)

• Henry II, 1002-1014 (crowned Emperor)

Salian dynasty

• Conrad II, 1024-1027 (crowned Emperor)

• Henry III, 1039-1046 (crowned Emperor)

• Henry IV, 1056-1084 (crowned Emperor)

• Henry V, 1105-1111 (in opposition to Henry IV 1105-1106; crowned Emperor 1111)

House of Supplinburg

• Lothair III, 1125-1133 (crowned Emperor)

House of Hohenstaufen

• Conrad III, 1127-1135 (in opposition to Lothair), 1138-1152 (died)

• Frederick I (Barbarossa) 1152-1155 (crowned Emperor)

• Henry VI 1190-1191 (crowned Emperor)

• Frederick II 1197 (deposed)

• Philip 1198-1208 (died 1208)

Welf dynasty

• Otto IV 1198-1208 (in opposition to Philip), 1208-1209 (crowned Emperor)

House of Hohenstaufen

• Frederick II 1212-1220 (crowned Emperor)

• Conrad IV 1250-1254 (died)

Great Interregnum

• Richard of Cornwall 1257-1272

• Alfonso of Castile 1257-1275

House of Habsburg

• Rudolph I 1273-1291 (died)

House of Nassau

• Adolph 1292-1298 (deposed and killed)

House of Habsburg

• Albert I 1298-1308 (died)

House of Luxembourg

• Henry VII 1308-1312 (crowned Emperor)

House of Habsburg

• Frederick the Fair 1314-1322 (opposed to Louis IV), 1326-1330 (jointly with Louis IV)

House of Wittelsbach

• Louis IV 1314-1328 (crowned Emperor)

House of Luxembourg

• Charles IV 1346-1347 (opposed to Louis V), 1347-1355 (crowned Emperor)

• Wenceslaus 1378-1400 (deposed)

House of Wittelsbach

• Rupert 1400-1410 (died)

House of Luxembourg

• Jobst of Moravia1410-1411 (opposed to Sigismund, died)

• Sigismund 1410-1411 (opposed to Jobst), 1411-1433 (crowned Emperor)

House of Habsburg

• Albert II 1438-1439 (died)

• Frederick III 1440-1452 (crowned Emperor)

• Maximilian I 1493-1508 (assumed Imperial title)

Title of the Heir designate

Royal succession in the Holy Roman Empire always was a difficult issue, since the Empire was an elective monarchy. However, once a ruler had been crowned Emperor, he could pursue the election of his heir as King, who would then succeed him after his death. This junior King, who usually did not participate in the rule, bore the title of a "King of the Romans".

This practice was continued even after 1556, when the rulers of the Holy Roman Empire no longer sought a coronation by the Pope and instead dubbed themselves Emperor-elect. Despite this lack of a coronation, the respective Emperor-elect's sons were elected during their fathers' lifetime in 1562, 1575, 1636, 1653, 1690, and in 1764.

Holy Roman Emperor under the Habsburgs

After the accession of Emperor Charles V, the Imperial title and the Empire became in effect, if not in law, exclusive Habsburg possessions. This meant that King of Rome or King of the Romans in turn effectively became the designation of the Habsburg heir-apparent. However, the Emperors after Charles V no longer sought Papal coronation, instead taking the title Emperor-elect upon accession; the title King of the Romans thereby ceased to be applied to reigning monarchs.

The practice was broken during the reigns of Emperor Joseph I and Emperor Charles VI, both of whom only produced daughters, and consequently were left without sons to have elected as King of the Romans. The latter designated his elder daughter, Maria Theresa of Austria, as his heiress in the hereditary Habsburg domains; however, the title of King of the Romans remained unfilled, and after Charles' death, the Electors chose the Elector of Bavaria as the new Emperor, Charles VII. After his death, Maria Theresa's husband, Francis Stephen, was elected Emperor; in 1764, in a resumption of tradition, he had his eldest son, Joseph, elected King of the Romans. However, Francis died a year later, and Joseph became Emperor. Due to Joseph's lack of sons, the swift death of his brother and successor (Leopold II), and the problems facing Leopold's son, Francis I, no other Habsburg after Joseph was ever elected 'King of Rome' or 'King of the Romans' prior to the dissolution of the Holy Roman Empire.

List of subordinate Kings of the Romans

The following were subordinate kings to another Holy Roman Emperor (usually, but not always, their father) for the dates specified. For those rulers of Germany who used the style King of the Romans, but were not subordinate to a Holy Roman Emperor, see List of German monarchs.

In the First French Empire

When Napoleon I of France had a son and heir, Napoleon II, he revived the title as King of Rome, styling his son as such. The boy was often known colloquially by the title throughout his short life, although after 1815 he was more commonly referred to as the Duke of Reichstadt.