- The Gauls, who sacked Rome in 390 BC.
- The Samnites, who fought a series of wars against Rome from 343 to 290 BC.
- The Carthaginians, who fought three wars against Rome from 264 to 146 BC.
- The Cimbri and Teutons, who invaded Italy in 113 BC.
- The Mithridates VI of Pontus, who fought three wars against Rome from 89 to 63 BC.
- The Gauls, who again invaded Italy in 60 BC.
- Julius Caesar, who crossed the Rubicon River in 49 BC and started a civil war that led to the fall of the Roman Republic.
- The Visigoths, who sacked Rome in 410 AD.
- The Vandals, who sacked Rome in 455 AD.
- The Ostrogoths, who conquered Italy in 493 AD.
- The Lombards, who invaded Italy in 568 AD.
- The Franks, who conquered Gaul in 486 AD and Italy in 774 AD.
- The Muslims, who conquered parts of Spain and Sicily in the 8th century AD.
- The Magyars, who invaded Italy in the 10th century AD.
- The Normans, who conquered England in 1066 AD and southern Italy in the 11th century AD.