Charlemagne was king of which Germanic tribe?

Charlemagne was king of the Franks, a Germanic people whose realm became the Carolingian Empire.

He inherited the Frankish kingship in 768, ruling jointly at first with his younger brother Carloman I. When Carloman died in 771, Charlemagne became sole king. Over the following decades, he expanded Frankish power through campaigns in Italy, Saxony, Bavaria, and other regions, creating one of the largest political realms in western Europe since the fall of the Western Roman Empire.

The Franks were not the same people as the Bavarians, Lombards, or Saxons, although Charlemagne fought or ruled all three groups at different times. The Lombards controlled much of northern Italy before Charlemagne conquered their kingdom in 774. The Saxons resisted Frankish expansion for more than 30 years, while Bavaria was incorporated into his realm in the late eighth century.

Charlemagne's royal title remained important even after Pope Leo III crowned him emperor in 800. Official documents described him as emperor while also identifying him as king of the Franks and the Lombards. His dynasty, the Carolingians, took its name from his grandfather Charles Martel.