King of Italy (Latin: Rex Italiae; Italian: Re d'Italia) was the title given to the ruler of the Kingdom of Italy after the fall of the Western Roman Empire. The first to take the title was Odoacer, a "barbarian" military leader, in the late 5th century, followed by the Ostrogothic kings up to the mid-6th century. With the Frankish conquest of Italy in the 8th century, the Carolingians assumed the title, which was maintained by subsequent Holy Roman Emperors throughout the Middle Ages. The last Emperor to claim the title was Charles V in the 16th century. During this period, the holders of the title were crowned with the Iron Crown of Lombardy.
Although Napoleon used the title from 1805 to 1814, it was not until the Unification of Italy in the 1860s that a Kingdom of Italy was restored. From 1861 the House of Savoy held the title as monarchs of the entire peninsula until the last King of Italy, Umberto II, abdicated in 1946 when Italy became a republic.
After the deposition of the last Western Emperor in 476, Heruli leader Odoacer was appointed Dux Italiae ("Duke of Italy") by the reigning Byzantine Emperor Zeno. Later, the Germanic foederati, the Scirians and the Heruli, as well as a large segment of the Italic Roman army, proclaimed Odoacer Rex Italiae ("King of Italy"). In 493, the Ostrogothic king Theoderic the Great killed Odoacer, and set up a new dynasty of kings of Italy. Ostrogothic rule ended when Italy was reconquered by the Byzantine Empire in 552.