The Romans are the native inhabitants of the region of Rome, the core of the greatest empire in the Ancient World, where Asterix stories are set. In a broader but more uncommon sense, a Roman is any person residing within the borders of the Roman Empire, which would include most Gauls, for example; but since Gauls and other peoples in the region are significantly patriotic and despise the Roman Empire, this term is rarely, or no applied at all to peoples outside the Roman peninsula in Asterix stories.
Roman soldiers are men who sworn their loyalty to the Roman Empire and Julius Caesar, their emperor. They are traditionally brute and merciless warriors towards other nations, and seek to expand their domines by conquering other peoples to the greatest extent as they can, to follow the orders of the emperor. The Roman Army is also known to be very well-trained and hierarchically organized, with titles given according to each soldier's deeds to the good of the empire.
With all their bellic power and large number of warriors, the Romans have successfully invaded much of Europe, North Africa and parts of Asia. All of the Gaulish nation is conquered, with the exception of the village lead by Vitalstatistix, where Asterix, Obelix and other characters dwell. This is the only place in Gaul that Romans never managed to invade, due to Getafix's magic potion, which is the secret weapon that provided super-human force to the Gaulish warriors.