The article examines the onomastic aspect of a medieval worldview through the analysis of naming principles for the kings of the Merovingian, the Carolingian and the Wessex dynasties. The etymological, structural and semantic analysis of the first Frankish and Anglo-Saxon kings' names and bynames is used. The etymology of the first Frankish and Anglo-Saxon kings' names is given, and the review of their bynames is made. Special emphasis is placed on the idea that the name chosen for the successor was aimed at preserving the dynastic succession and the legitimization of power. In addition, king's personal charisma was strengthened through a proper noun. The ways of analysis are useful for development of contrastive and historical linguistics, theory of linguistics, naming theory.