Question: What do you call the ruler of Germany?

List of German monarchs

This is about monarchs ruling over all of Germany; for the much more extensive number of monarchs ruling territories within Germany, see List of states in the Holy Roman Empire, Princes of the Holy Roman Empire, List of historic states of Germany.

This is a list of monarchs who ruled over East Francia, and the Kingdom of Germany (Regnum Teutonicum), from the division of the Frankish Empire in 843 until the dissolution of the Holy Roman Empire in 1806. 
The title used by the early rulers was Rex Francorum orientalium, "King of the East Franks", or Rex Francorum "King of the Franks". During the later medieval period (11th to 15th centuries), the title was "King of the Romans" (Rex Romanorum), and sometimes, interchangeably, "King of the Germans" (Rex Teutonicorum). 
From 1508 until 1806, "King of the Romans" continued to be used by the emperor, while Rex Germaniae "King of Germany" or Rex in Germania "King in Germany" was used by the emperor's heir-apparent.
Also listed are the heads of the various German confederations between the dissolution of the Holy Roman Empire (of which Germany was a part) in 1806 until the collapse of the German Empire in 1918. 
Note on titles
The Kingdom of Germany started out as the eastern section of the Frankish kingdom, which was split by the Treaty of Verdun in 843. The rulers of the eastern area thus called themselves rex Francorum, king of the Franks, and later just rex. A reference to the "Germans", indicating the emergence of a German nation of some sort, did not appear until the eleventh century, when the pope referred to his enemy Henry IV as rex teutonicorum, king of the Germans, in order to brand him as a foreigner. The kings reacted by consistently using the title rex Romanorum, King of the Romans, to emphasize their universal rule even before becoming emperor. This title remained until the end of the Empire in 1806, though after 1508 Emperors-elect added "king in Germany" to their titles. (Note: in this and related entries, the kings are called kings of Germany, for clarity's sake)
The Kingdom of Germany was never entirely hereditary; rather, ancestry was only one of the factors that determined the succession of kings. During the 10th to 13th centuries, the king was formally elected by the leading nobility in the realm, continuing the Frankish tradition. Gradually the election became the privilege of a group of princes called electors, and the Golden Bull of 1356 formally defined election proceedings.[1]
In the Middle Ages, the king did not assume the title "Emperor" (since 982 the full title was Imperator Augustus Romanorum, Venerable Emperor of the Romans) until crowned by the pope. Moving to Italy, he was usually first crowned with the Iron Crown of Lombardy, after which he assumed the title of rex Italiae, King of Italy. After this he would ride on to Rome and be crowned emperor by the pope. See Coronation of the Holy Roman Emperor for more details.
The title of "King of the Germans" (rex teutonicorum) was in use from the 11th until the 18th centuries, in origin a derogatory replacement of King of the Romans (rex romanorum) imposed on Henry IV by Pope Gregory VII, in the later period a nominal title given to the heir apparent of the ruling emperor.
Maximilian I was the first king to bear the title of Elected Emperor. After the failure in 1508 of his attempt to march to Rome and be crowned by the pope, he had himself proclaimed Elected Emperor with papal consent. His successor Charles V also assumed that title after his coronation in 1520 until he was crowned emperor by the pope in 1530. From Ferdinand I onwards, all emperors were Elected Emperor, although they were normally referred to as emperors. At the same time, chosen successors of the emperors held the title of king of the Romans, if elected by the college of electors during their predecessor's lifetime. See King of the Romans for more details.
Emperors are listed in bold. Rival kings, anti-kings, and junior co-regents are italicized.
East Francia, 843–962
Carolingians

Conradines

Ottonian dynasty

Holy Roman Empire, 962–1806
The title "King of the Romans", used under the Holy Roman Empire, is considered equivalent to King of Germany. A king was chosen by the German electors and would then proceed to Rome to be crowned emperor by the pope.
Ottonian dynasty (continued)

Salian dynasty

Supplinburger dynasty

Hohenstaufen and Welf

Interregnum


Habsburg and Nassau

Luxembourg and Wittelsbach

Habsburg

Wittelsbach

Habsburg-Lorraine

Modern Germany, 1806–1918
Confederation of the Rhine, 1806–1813

German Confederation, 1815–1866

North German Confederation, 1867–1871

German Empire, 1871–1918

See also
Kings of Germany family tree
List of German monarchs in 1918
List of German queens
List of rulers of Austria
List of rulers of Bavaria
List of monarchs of Prussia
List of rulers of Saxony
List of rulers of Württemberg
Footnotes