Hastings' Dictionary of the Bible 
ONIAS . Four high priests bore this name. Onias I . was son of Jaddua and father of Simon the Just ( Sir 50:1 , where, however, the Heb. reads John in place of Onias ). In his time a letter was said to have come from the Spartan king Areus I. claiming kinship and suggesting alliance ( 1Ma 12:7 f. [RV [Note: Revised Version.] . Arius ]; cf. Jos. [Note: Josephus.] Ant . XII. iv. 10). Onias II . was son of Simon the Just. His reluctance to pay the tribute of 20 talents to Egypt would have led to great trouble if his shrewd and self-seeking nephew Joseph had not conciliated Ptolemy ( Ant . XII. vi. 1). Onias III. was son of Simon II., and entered on his office about b.c. 198. According to 2M Malachi 3:1 to 2Ma 4:38 , he ruled the city well. A dispute arose between him and a man named Simon. The latter persuaded king Scleucus to send Heliodorus ( 4Ma 4:1-14 substitutes Apollonius ) to seize the Temple treasury. Heliodorus being supernaturally repulsed, Onias went to Antioch to defend himself. He was deposed from his office. In b.c. 175 he was murdered ( Daniel 9:26 ). The esteem in which his memory was held appears from 2Ma 15:12-14 . His son Onias IV. fled to Egypt and was welcomed by Ptolemy Philometor, who gave him a disused temple in Leontopolis, which he re-built after the model of the one in Jerusalem, to serve as a centre of unity for the Hellenistic Jews ( Ant . XIII. iii. 1, 3, BJ I. i. 1, VII. x. 2).
Smith's Bible Dictionary 
Oni'as. The name of five high priests, in the period between the Old and the New Testament.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
( Ο᾿Νίας . perh. for אַנַיָּה , a Ship ) , the name of five Jewish pontiffs, mentioned by the Apocrypha and by Josephus. The following account of tlhemI Is mostly from those authorities. (See High-Priest).
1. The son and successor of Jaddua, who entered on the office about the time of the death of Alexander the Great, B.C. cir. 330-309, or, according to Eusebius, 300 (Josephus, Ant. 11:7, 7). According to Josephus he was father of Simon the Just ( Ant. 12:2, 4; comp. Sirach 1, 1). (See Simon).
2. The son of Simon the Just (Josephus, Ant. xii 4, 1). He was a minor at the time of his father's death (B.C. cir. 290), and the high-priesthood was occupied in succession by his uncles Eleazar and Manasseh to his exclusion. He entered on the office at last (B.C. cir. 240), and his conduct threatened to precipitate the rupture with Egypt which afterwards opened the way for Syrian oppression. Onias, from avarice, it is said — a vice which was likely to be increased by his long exclusion from power — neglected for several years to remit to Ptolemy Euergetes the customary annual tribute of 20 talents. The king claimed the arrears with threats of violence in case his demands were not satisfied. Onias still refused to discharge the debt, more, asit appears, from self-will than with any prospect of successful resistance. The evil consequences of this obstinacy were, however, averted by the policy of his nephew Joseph, the son of Tobias, who visited Ptolemy, urged the imbecility of Onias, won. the favor of. the king, and entered into a contract for farming the tribute, which he carried out with success. Onias retained the high-priesthood till his death (B.C. cir. 226), when he was succeeded by his son Simon II (Josephus, Ant. 12:4).
3. The son of Simon II, who succeeded his father in the high-priesthood. B.C. cir. 198. In the interval which had elapsed since the government of his grandfather the Jews had transferred their allegiance to the Syrian monarchy ( Daniel 11:14), and for a time enjoyed tranquil prosperity. Internal dissensions furnished an occasion for the first act of oppression. Seleucus Philopator was informed by Simon, governor of the Temple, of the riches contained in the sacred treasury, and he made an attempt to seize them by force. At the prayer of Onias, according to the tradition ( 2 Maccabees 3:1), the sacrilege was averted; but the high-priest was obliged to appeal to the king himself for support against the machinations of Simon. Not long afterwards Seleucus died (B.C. 175), and Onias found himself supplanted in the favor of Antiochus Epiphanes by his brother Jason, who received the high-priesthood from the king. Jason, in turn, was displaced by his youngest. brother Menelaus, who procured the murder of Onias (B.C. cir. 171), in anger at the reproof which he had received from him for his sacrilege ( 2 Maccabees 4:32-38). But though his righteous zeal was thus fervent, the punishment which Antiochus inflicted on his murderer was a tribute to his "sober and modest behavior" ( 2 Maccabees 4:37) after his deposition from his office. (See Andronicus).
It was probably during the government of Onias III that the communication between the Spartans and Jews took place ( 1 Maccabees 12:19-23; Josephus, Ant. 12:4, 10). (See Spartans). How powerful an impression he made upon his. contemporaries is seen from the remarkable account of the dream of Judas Maccabaeus before his great victory ( 2 Maccabees 15:12-16).
4. The youngest brother of Onias III, who bore the same name, which he afterwards exchanged for Menelaus (Josephus, Ant. 12:5,1). (See Menelaus).
5. The son of Onias III, who sought a refuge in Egypt from the sedition and sacrilege which disgraced Jerusalem. The immediate occasion of his flight was the triumph of "the sons of Tobias," gained by the interference of Antiochus Epiphanes. Onias, to whom the high-priesthood belonged by right, appears to have supported throughout the alliance with Egypt (Josephus, War, 1:1, 1), and receiving the protection of Ptolemy Philometor, he endeavored to give a unity to the Hellenistic Jews which seemed impossible for the Jews in Palestine. With this object he founded the temple at Leontopolis, which occupies a position in the history of the development of Judaism of which the importance is commonly overlooked; but the discussion of this attempt to consolidate Hellenism belongs to another place, though the connection of the attempt itself with Jewish history could not be wholly overlooked (Josephus, Ant. 13:3; War, l, c, 1; 7:10, 2; comp. Ewald, Gesch. 4:405 sq.; Herzfeld, Gesch. ii, 460 sq., 557 sq.).
International Standard Bible Encyclopedia 
ṓ - nı̄´as ( Ὀνίας , Onı́as ): There were 3 high priests of the name of Onias, and a 4th Onias who did not become a high priest but was known as the builder of the temple of Leontopolis (Josephus, Ant. , Xiii , iii, 1-3). Only two persons of the name are mentioned in the Apocrypha - O nias I and Onias III.
(1) Onias I, according to Josephus ( Ant. , XI, viii, 7), the son of Jaddua and father of Simon the Just (ibid., Xii , ii, 5; Sirach 50 ), and, according to 1 Maccabees 12:7,20 , a contemporary of Areus (Arius), king of Sparta, who reigned 309-265 Bc (Diod. xx.29). This Onias was the recipient of a friendly letter from Areus of Sparta ( 1 Maccabees 12:7; see manuscripts readings here, and 12:20). Josephus ( Ant. , Xii , iv, 10) represents this letter as written to Onias III, which is an error, for only two Areuses are known, and Areus 2 reigned about 255 Bc and died a child of 8 years (Paus. iii. 6,6). The letter - if genuine - exists in two copies (Josephus, Ant. , Xii , iv, 10, and 1 Maccabees 12:20 ff) (see Schurer, History of the Jewish People , 4th edition, I, 182,237).
(2) Onias III, son of Simon 2 (Josephus, Ant. , Xii , iv, 10), whom he succeeded, and a contemporary of Seleucus 4 and Antiochus Epiphanes ( 2 Maccabees 3:1; 4:7 ) and father of Onias IV. He was known for his godliness and zeal for the law, yet was on such friendly terms with the Seleucids that Seleucus 4 Philopator defrayed the cost of the "services of the sacrifices." He quarreled with Simon the Benjamite, guardian of the temple, about the market buildings (Greek aedileship). Being unable to get the better of Onias and thirsting for revenge, Simon went to Apollonius, governor of Coele-Syria and Phoenicia, and informed him of the "untold sums of money," lodged in the treasury of the temple. The governor told the king, and Seleucus dispatched his chancellor, Heliodorus, to remove the money. Onias remonstrated in vain, pleading for the "deposits of widows and orphans." Heliodorus persisted in the object of his mission. The high priest and the people were in the greatest distress. But when Heliodorus had already entered the temple, "the Sovereign of spirits, and of all authority caused a great apparition," a horse with a terrible rider accompanied by two strong and beautiful young men who scourged and wounded Heliodorus. At the intercession of Onias, his life was spared. Heliodorus advised the king to send on the same errand any enemy or conspirator whom he wished punished. Simon then slandered Onias, and the jealousy having caused bloodshed between their followers, Onias decided to repair in person to the king to intercede for his country. Apparently before a decision was given, Seleucus was assassinated and Epiphanes succeeded (175 BC). Jason, the brother of Onias, having offered the new king larger revenue, secured the priesthood, which he held until he himself was similarly supplanted by Menelaus, Simon's brother ( 2 Maccabees 4:23; Josephus, Ant. , Xii , v, 1, says Jason's brother). Menelaus, having stolen golden vessels belonging to the temple to meet his promises made to the king, was sharply reproved by Onias. Menelaus took revenge by persuading Andronicus, the king's deputy, to entice Onias by false promises of friendship from his sanctuary at Daphne and treacherously slay him - an act which caused indignation among both the Jews and the Greeks ( 2 Maccabees 4:34 ff). Josephus ( Ant. , Xii , v, 1) says that "on the death of Onias the high priest, Antiochus gave the high-priesthood to his brother Jesus (Jason)," but the account of 2 Macc given above is the more probable. Some see in Daniel 9:26; Daniel 11:22 reference to Onias Iii (Schurer, 4th edition, I, 194 ff; III, 144).