Hastings' Dictionary of the Bible 
HELIODORUS . The chancellor of Seleucus iv. Philopator. At the instigation of Apollonius he was sent by the king to plunder the private treasures kept in the Temple of Jerus.; but was prevented from carrying out his design by an apparition ( Malachi 3:7 Malachi 3:7 ff.). In b.c. 175. Heliodorus murdered Seleucus, and attempted to seize the Syrian crown; but he was driven out by Eumenes of Pergamus and his brother Attalus; and Antiochus Epiphanes, brother of Seleucus, ascended the throne. There is commonly supposed to be a reference to Heliodorus in Daniel 11:20 , but the interpretation of the passage is doubtful. Further, he is frequently reckoned as one of the ten or the three kings of Daniel 7:7 f.
International Standard Bible Encyclopedia 
hē - 51 - ō̇ - dō´rus ( Ἡλιόδωρος , Hēliódōros ): Treasurer of the Syrian king Seleucus IV, Philopator (187-175 bc), the immediate predecessor of Antiochus Epiphanes who carried out to its utmost extremity the Hellenizing policy begun by Seleucus and the "sons of Tobias." Greatly in want of money to pay the tribute due to the Romans as one of the results of the victory of Scipio over Antiochus the Great at Magnesia (190 bc), Seleucus learned from Apollonius, governor of Coele-Syria (Pal) and Phoenicia, of the wealth which was reported to be stored up in the Temple at Jerusalem and commissioned Heliodorus. ( 2 Maccabees 3 ) to plunder the temple and to bring its contents to him. On the wealth collected in the Temple at this time, Josephus ( Ant. , IV, vii, 2) may be consulted. The Temple seems to have served the purposes of a bank in which the private deposits of widows and orphans were kept for greater security, and in 2 Maccabees 3:15-21 is narrated the panic at Jerusalem which took place when Heliodorus came with an armed guard to seize the contents of the Temple (see Stanley, Lectures on the History of the Jewish Church , III, 287). In spite of the protest of Onias, the high priest, Heliodorus. was proceeding to carry out his commission when, "through the Lord of Spirits and the Prince of all power," a great apparition appeared which caused him to fall down "compassed with great darkness" and speechless. When "quite at the last gasp" he was by the intercession of Onias restored to life and strength and "testified to all men the works of the great God which he had beheld with his eyes." The narrative given in 2 Maccabees 3 is not mentioned by any other historian, though 4 Macc refers to the plundering of the Temple and assigns the deed to Apollonius. Raffaelle used the incident in depicting, on the walls of the Vatican, the triumph of Pope Julius 2 over the enemies of the Pontificate.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
( ᾿Ηελιόδωρος , i.e. Gift Of The Sun, a not unfrequent Greek name), the treasurer ( Ὁ Ἐπὶ Τῶνπραγμάτων ) of Seleucus Philopator, who was commissioned by the king, at the instigation of Apollonius (q.v.), to carry away the private treasures deposited in the Temple at Jerusalem. According to the narrative in 2 Maccabees 3:9 sq., he was stayed from the execution of his design by a "great apparition" ( Ἐπιφάνεια ), in consequence of which he fell down "compassed with great darkness," and speechless. He was afterwards restored at the intercession of the high- priest Onias, and bore witness to the king of the inviolable majesty of the Temple (2 Maccabees 3). The full details of the narrative are not supported by any other evidence. Josephus, who was unacquainted with 2 Macc., takes no notice of it (Ant. 12, 3, 3); and the author of the so called 4 Macc. attributes the attempt to plunder the-Temple to Apollonius, and differs in his account of the miraculous interposition, though he distinctly recognizes it (De Mltcc. 4 Οὐρανόθεν Ἔφιπποι Προυφάνησαν Ἄγγελοι .... Καταπεσὼν Δὲ Ἡμιθανὴς Οα῾᾿Πολλώνιος .. ). Heliedorus afterwards murdered Seleucus, and made an unsuccessful attempt to seize the Syrian crown (App. Syr. 45). B.C. 175. — Comp. Wernsdorf, De Ide Libr. Macc. § liv. Raffaelle's grand picture of "Heliodorus" has often been copied and engraved.
The Nuttall Encyclopedia 
The most noted and earliest of the Greek romancists, born at Emesa, Syria; flourished in the second half of the 3rd century A.D.; his romance "Æthiopica" is a love tale of great beauty and told with naïve simplicity; has had considerable influence over subsequent romance writers, e. g . Tasso.