(Canto 12, lines 134-135)
Attila, the fifth century ruler of the Huns popularly known as the "scourge of God". In 434, he became the ruler of the Huns together with his elder brother Bleda, whom he however murdered in 442 to take power himself. He ravaged the Eastern Roman Empire in 447 and penetrated into Gaul in 451, but was eventually stopped by the Roman general Aëtius. In 452, he invaded Italy with his forces, but was persuaded to retreat by Pope Saint Leo I. Attila died in 453, supposedly while celebrating his own marriage.
We cannot be sure if Pyrrhus here refers to the Macedonian Pyrrhus of Epirus (319-272 BC) or the son of Achilles, who killed Priamus and his children together with many other Trojans during the siege of Troy. Because the former is praised in by Dante in De Monarchia, the case for the latter, mentioned in the Aeneid, is perhaps stronger.
Sextus is probably the son of Pompey, who was variously portrayed for his cruelty, but it may also be the son of the Roman king Tarquinius Superbus, the ravisher of Lucrece.