In reply to:
The surname Roman in Spain originated c. 750 in the coastal village of Ortigueira in Galicia, near Portugal. The earliest was Roman Freula, nephew of King Freula.
The surname was brought over from France to the Britsh Isles with the Norman Invasion in 1054.
There are Romanian Romans, Polish Romans. In Italy it's Roman, in Portugal Romao, in France, Romaine.
It seems that the Roman surnames originated throughout Europe somtime after the fall of the Roman Empire.