(Προυσίας), king of Bithynia, was the son and successor of the preceding. No mention is found in any extant author of the period of his accession, and we only know that it must have been subsequent to B. C. 183, as Strabo distinctly tells us (xii. p. 563), that the Prusias who received Hannibal at his court, was the son of Zielas. In B. C. 179, we find the name of Prusias associated with Eumenes in the treaty concluded by that monarch with Pharnaces, king of Pontus (Plb. 26.6), and this is supposed by Clinton to be the younger Prusias. It is certain, at least, that he was already on the throne before the breaking out of the war between the Romans and Perseus, B. C. 171. Prusias had previously sued for and obtained in marriage a sister of the Macedonian king, but notwithstanding this alliance he determined to keep aloof from the impending contest, and await the result with a view to make his peace with whichever party should prove victorious. (Liv. 42.12, 29; Appian, App. Mith. 2.) In B. C. 169, however, he ventured to send an embassy to Rome, to interpose his good offices in favour of Perseus, and endeavour to prevail upon the senate to grant him a peace upon favourable terms. His intervention, however, was haughtily rejected, and fortune having the next year decided in favour of the Romans, Prusias sought to avert any offence he might have given by this ill-judged step, by the most abject and sordid flatteries. He received the Roman deputies who were sent to his court, in the garb which was characteristic of an emancipated slave, and styled himself the freedman of the Roman people: and the following year, B. C. 167, he himself repaired to Rome, where he sought to conciliate the favour of the senate by similar acts of slavish adulation. By this meanness he disarmed the resentment of the Romans, and obtained a renewal of the league between him and the republic, accompanied even with an extension of territory. (Plb. 30.16 ; Liv. 45.44; Diod. xxxi. Exc. Vat. p. 83, Exc. Legat. p. 565; Appian. Mithr. 2; Eutrop. 4.8 ; Zonar. 9.24.)

From this time we find Prusias repeatedly sending embassies to Rome to prefer complaints against Eumenes, which, however, led to no results (Plb. 31.6, 9, 32.3, 5), until, at length, in B. C. 156, after the death of Eumenes, the disputes between his successor Attalus and the Bithynian king broke out into open hostilities. In these Prusias was at first successful, defeated Attalus in a great battle, and compelled him to take refuge in Pergamus, to which he laid siege, but without effect. Meanwhile, Attalus had sent to Rome to complain of the aggression of the Bithynian king, and an embassy was sent by the senate, to order Prusias to desist: but he treated this command with contempt, and attacking Attalus a second time, again drove him within the walls of Pergamus. But the following year the arms of Attalus were more successful, and a fresh embassy from the senate at length compelled Prusias to make peace, B. C. 154. (Plb. 32.25, 26, xxxiii. l, 10, 11; Appian. Mithr. 3; Diod. xxxi. Exc. Vales. p. 589.) Meanwhile, the Bithynian monarch had alienated the minds of his subjects by his vices and cruelties, and his son Nicomedes had become the object of the popular favour and admiration. This aroused the jealousy and suspicion of the old king, who, in order to remove his son from the eyes of his countrymen, sent him to Rome: and subsequently, as his apprehensions still increased, gave secret instructions to his ambassador Menas to remove the young prince by assassination. Menas, however, finding how high Nicomedes stood in the favour of the Roman senate, attached himself to the cause of the prince, and united with Andronicus the ambassador of Attalus in an attempt to establish Nicomedes on the throne of Bithynia. Prusias was unable to make head against the disaffection of his own subjects, supported by the arms of Attalus, and after an ineffectual appeal to the intervention of the Romans, who secretly favoured Nicomedes, shut himself up within the walls of Nicomedia. The gates were, however, opened by the inhabitants, and Prusias himsell was slain in a temple, to which he had fled for refuge. His death took place in B. C. 149. (Appian. Mithr. 4-7; Just. 34.4; Liv. Epit. l.; Diod. xxxii. Exc. Phot. p. 523; Zonar. 9.28.)

Prusias II. is described to us as a man in whom personal deformity was combined with a character the most vicious and degraded, and all ancient authors concur in representing him as the slave of every vice that was contemptible in a snan, or odious in a king. His passion for the chase is attested by the epithet of the "Huntsman" (Κυνηγός), by which he is sometimes designated. (Plb. 30.16, 37.2; Diod. xxxii. Exc. Vales. p. 591; Appian. Mithr. 2, 4; Liv. Epit. l.; Athen. 11.496. d.)

The chronology of the reigns of the two kings who bore the name of Prusias is very obscure : the earlier writers, such as Reinerus and Sigonius, even confounded the two, and supposed that there was only one king of Bithynia of this name. Valesius (ad Polyb. 37.2) was the first to point out this error : and the subject has since been fully investigated by Mr. Clinton (F. H. vol. iii. pp. 413, 418.) If we adopt the view of the last author, we may assign to the elder Prusias a reign of about 48 years (B. C. 228-180), and of 31 years to the younger (180-149). But of these dates the only one that can be fixed with certainty is that of the death of Prusias II.