Question: Which first King of Italy  was  Caecina Mavortius Basilius Decius a Roman politician under

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Caecina (gens): Caecina was the name of an Etruscan family of Volaterrae, one of the ancient cities of Etruria.  Persons of this gens are first mentioned in the first century BC.  Under the Empire the name is of frequent occurrence.  As late as the reign of Honorius, we read of the poet Decius Albinus Caecina, residing at his villa in the neighborhood of Volaterrae; and until modern times there has been a family of this name at the modern Volterra.  The family tomb of the Caecinae has been discovered in the neighborhood of Volterra; in this tomb there was found a beautiful sarcophagus, now in the Museum of Paris.

Publius Decius Mus (consul 279 BC): Publius Decius Mus was a Roman politician and general of the plebeian gens Decia.  He was the son of Publius Decius Mus, who was consul in 312 BC.  As consul in 279 BC, he and his fellow consul, Publius Sulpicius Saverrio, combined their armies against Pyrrhus of Epirus at the Battle of Asculum.  Pyrrhus was victorious, but at such a high cost that the security of Asculum was guaranteed.  This is the origin of the term "Pyrrhic victory".  According to one tradition, Decius died in the field; according to another, he survived.

Battle of Saticula: The Battle of Saticula, 343 BC, was the second of three battles described by the Roman historian Livy (59 BC – AD 17), in Book Seven of his history of Rome, Ab Urbe Condita, as taking place in the first year of the First Samnite War.  According to Livy's extensive description, the Roman commander, the consul Aulus Cornelius Cossus was marching from Saticula (in southern Italy) when he was almost trapped by a Samnite army in a mountain pass.  His army was only saved because one of his military tribunes, Publius Decius Mus, led a small group of men to seize a hilltop, distracting the Samnites and allowing the consul to escape.  During the night Decius and his men were themselves able to escape.  The next day the reunited Romans attacked the Samnites and completely routed them.  Several other ancient authors also mention Decius' heroic acts.  Modern historians are however sceptical of the historical accuracy of Livy's account, and have in particular noted the similarities with how a military tribune is said to have saved Roman army in 258 BC during the First Punic War.

Caecina Decius Basilius: Flavius Caecina Decius Basilius ("floruit" 458-468) was a politician of the Western Roman Empire, Consul and twice Praetorian prefect of Italy.

Caecina Mavortius Basilius Decius: Caecina Mavortius Basilius Decius ("floruit" 486-510) was a Roman politician under Odoacer's rule.  He was consul and "Praefectus urbi" of Rome in 486 and Praetorian prefect of Italy from 486 to 493.

Caecina Decius Maximus Basilius: Caecina Decius Maximus Basilius ("floruit" 483–500), was a Roman politician.  He was the first consul appointed under Odoacer's rule (480), and afterwards was Praetorian prefect of Italy.  He is best known for presiding over the papal election of Pope Felix III.

Vettius Agorius Basilius Mavortius: Vettius Agorius Basilius Mavortius (floruit 527–534) was a Roman aristocrat who lived during Ostrogothic rule.  He was appointed consul for 527.

Albinus (consul 493): Albinus, or Caecina Decius Faustus Albinus, ("floruit" 490–525) was a Roman politician during the reign of Theodoric the Great.  He held the consulship with Flavius Eusebius in 493.  Albinus is best known for being identified with the senator whom Boethius defended from accusations of treasonous correspondence with the Eastern Roman Empire by the "referandarius" Cyprianus -- only to have Cyprianus then accuse Boethius of the same crime.

Rufius Postumius Festus: Rufius Postumius Festus (fl.  472-507) was a Roman aristocrat who lived during the Late Roman Empire.  Festus was the last consul appointed by an Emperor in the West.  The next consul appointed in the West was Caecina Decius Maximus Basilius, whom king Odoacer appointed in 480, eight years after Festus.

Odoacer: Flavius Odoacer (c. 433 – 493 AD), also known as Flavius Odovacer or Odovacar (Italian: "Odoacre" , Latin: "Odoacer, Odoacar, Odovacar, Odovacris" ), was a soldier who in 476 became the first King of Italy (476–493).  His reign is commonly seen as marking the end of the Western Roman Empire.  Though the real power in Italy was in his hands, he represented himself as the client of the Emperor in Constantinople.  Odoacer generally used the Roman honorific "patrician," granted by the Emperor Zeno, but is referred to as a king (Latin: "rex" ) in many documents and he himself used it in the only surviving official document emanated from his chancery; also it was used by the consul Basilius.  Odoacer introduced few important changes into the administrative system of Italy.  He had the support of the Roman Senate and was able to distribute land to his followers without much opposition.  Unrest among his warriors led to violence in 477–478, but no such disturbances occurred during the later period of his reign.  Although Odoacer was an Arian Christian, he rarely intervened in the affairs of the orthodox and trinitarian state church of the Roman Empire.

Supporting paragraphs: Caecina Mavortius Basilius Decius Odoacer
Answer: Flavius Odoacer