A Frankish ruler was a leader of the Franks, a group of Germanic tribes that played a significant role in the early medieval period in Europe. The most notable Frankish ruler was Charlemagne, who expanded the Frankish kingdom and became the first Holy Roman Emperor. Frankish rulers were known for their military prowess and efforts to unite various tribes under a single kingdom. These rulers often promoted Christianity and worked closely with the Catholic Church to strengthen their authority. The Frankish Empire laid the foundation for modern European nations and influenced the development of feudalism, which shaped the social and political landscape of medieval Europe.