After his family is destroyed in rebellion, Superbus dies an unremarkable death:
Publicola, serving for a third time as consul, continually called Tarquinius to justice, censuring him as the basest man who had rightly fallen from power; Lars Porsenna served as the judge. When Tarquinius responded that he would not accept Porsenna as a judge if he were to be cast off as an ally, Porsenna pronounced his verdict and stopped the war. Even after all of this, the Tarquins tried repeatedly to retake the throne, fighting quite often with the assistance of Rome’s neighbors; all of the Tarquins died in these battles, with the exception of the eldest, Tarquinius Superbus. A Greek man would call him, ‘ὑπερήφανος’ (‘the Arrogant’). He later went to Cumae, in Opicia[i], where he died.
[i] For Opicia, see Arist.Pol.1329b19: The ‘Opicoi’ were later the ‘Ausonians’ of southern Italy.
῾Ο δὲ Ποπλικόλας τὸ τρίτον ὑπατεύων τότε προυκαλεῖτο συνεχῶς τὸν Ταρκύνιον ἐπὶ δίκῃ, ὡς ἐξελέγξων κάκιστον καὶ ἐκπεπτωκότα τῆς ἀρχῆς ἐνδικώτατα, τοῦ Πορσίνου δικάζοντος. ἀποκριναμένου δὲ Ταρκυνίου μὴ αἱρεῖσθαι Πορσίναν διαιτητήν, εἰ σύμμαχος ὢν μεταβάλλεται, καταγνοὺς ὁ Πορσίνας τὸν πόλεμον κατελύσατο. καὶ μετὰ ταῦτα δὲ πολλάκις μὲν ἐπεχείρησαν οἱ Ταρκύνιοι τὴν βασιλείαν ἀναλαβεῖν, τοῖς ὁμοροῦσι ῾Ρωμαίοις ἔθνεσι συμμαχούμενοι, πάντες δὲ ἐν ταῖς μάχαις ἐφθάρησαν, πλὴν τοῦ γέροντος, ὃς καὶ Σούπερβος ἐκαλεῖτο· εἴποι ἄν τις ῞Ελλην ἀνήρ, ὑπερήφανος. κἀκεῖνος δὲ μετέπειτα εἰς Κύμην τὴν ἐν ᾿Οπικίᾳ γενόμενος ἐτελεύτησεν.