The Electoral Palatinate was a constituent state of the Holy Roman Empire until it was annexed by the Electorate of Baden in 1803. From the end of the 13th century, its ruler was one of the Prince-electors who elected the Holy Roman Emperor, ranking them among the most significant secular Princes of the Holy Roman Empire.

The Palatinate consisted of a number of widely dispersed territories, ranging from the left bank of the Upper Rhine in the modern state of Rhineland-Palatinate, adjacent parts of the French regions of Alsace and Lorraine to the opposite territory on the east bank of the Rhine in present-day Hesse and Baden-Württemberg up to the Odenwald range and the southern Kraichgau region, containing the capital cities of Heidelberg and Mannheim.

In 1541, Otto Henry, Elector Palatine converted to Lutheranism, while his Calvinist descendant, Frederick V, sparked the Thirty Years' War in 1618 by accepting the Crown of Bohemia. Occupied until the 1648 Peace of Westphalia, the Palatinate suffered extensive damage during the 1688 to 1697 Nine Years' War. Ruled in personal union with the Electorate of Bavaria from 1777, the Palatinate was annexed by Baden in 1803, before being absorbed by Bavaria in 1805.

A position of Count Palatine at the Frankish court of King Childebert I was mentioned about 535. The Counts Palatine were the permanent representatives of the king in particular geographic areas, in contrast to the semi-independent authority of the dukes (and their successors). Under the Merovingian dynasty, the position had been a purely appointed one, but by the Middle Ages had evolved into an hereditary one.

Up to the tenth century, the Frankish empire was centered at the royal palace (Pfalz) in Aachen, in what had become the Carolingian kingdom of Lotharingia. Consequently, the Count Palatine of Lotharingia became the most important of the Counts Palatine. Marital alliances meant that, by the Middle Ages, most Count Palatine positions had been inherited by the duke of the associated province, but the importance of the Count Palatine of Lotharingia enabled it to remain as an independent position.

In 985, Herman I, a scion of the Ezzonids, is mentioned as count palatine of Lotharingia (which by then had been divided into Upper and Lower Lotharingia). While his Palatine authority operated over the whole of Upper Lorraine, the feudal territories of his family were instead scattered around south-western Franconia, including parts of the Rhineland around Cologne and Bonn, and areas around the rivers Moselle and Nahe.

In continual conflicts with the rivalling Archbishops of Cologne, he changed the emphasis of his rule to the southern Eifel region and further to the Upper Rhine, where the Ezzonid dynasty governed several counties on both banks of the river. The southernmost point was near Alzey.

From about 1085/86, after the death of the last Ezzonian count palatine Herman II, Palatinate authority ceased to have any military significance in Lotharingia. In practice, the Count Palatinate's Palatine authority had collapsed, reducing his successor (Henry of Laach) to a mere feudal magnate over his own territories – along the Upper Rhine in south-western Franconia. From this time on, his territory became known as the County Palatine of the Rhine (not because Palatine authority existed there, but as an acknowledgement that the Count still held the title, if not the authority, of Count Palatine).