What was Charlemagne's last name?

Charlemagne was born around 747 AD and named Charles after his grandfather Charles Martel. In those days family surnames had not yet been adopted and people were known by nicknames to distinguish them from other people with the same name. Charles became known as Charles the Great or Carolus Magna. English historians translated this as Charlemagne.

Charlemagne's full name was Charles Merovingian