Charles m. Old High German karl 'man', Old English c(e)arl, ceorl 'freeman'.
The name of numerous kings and emperors in France, Germany, Hungary, Sweden, England, Portugal, Norway, Bohemia, Spain, and Italy, a 12th C Flemish saint, a 14th C Breton saint, and a 16th C Italian saint.
The prominence of Charles the Great (Charlemagne) helped contribute to the name's enduring popularity.