From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

HOLOFERNES . According to the Book of Judith, Holofernes was the general entrusted by Nehuchadnezzar, ‘king of Nineveh,’ with the task of wreaking vengeance on ‘all the earth’ ( Jdt 2:1; Jdt 2:4 ). Before his vast army nation after nation submitted and acknowledged Nehuchadnezzar as a god. The Jews alone would not yield; and Holofernes accordingly blockaded their city of Bethulia. For the subsequent story and the death of Holofernes at the hands of Judith, see art. Judith.

Holofernes has been variously identified with Ashurbanipal, Cambyses, Orophernes of Cappadocia (a friend of Demetrius Soter, the enemy of the Jews), Nicanor (the Syrian general conquered by Judas Maccahæus), Scaurus (Pompey’s lieutenant in Syria), and Severus (Hadrian’s general).

W. M. Nesbit.

Smith's Bible Dictionary [2]

Holofer'nes. Holofernes, or more correctly, Olofernes , was, according to the book of Judith, a general of Nebuchadnezzar, king of the Assyrians,  Judith 2:4, who was slain by the Jewish heroine, Judith, during the siege of Bethulia. (B.C. 350).

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [3]

Or, rather, OLOFERNES ( Ο᾿Λοφέρνης ), a person mentioned only in the Apocrypha ( Judith 2:4, etc.). The name occurs twice in Cappadocian history, as borne by the brother of Ariarathes I (B.C. cir. 350), and afterwards by a pretender to the Cappadocian throne, who was at first supported and afterwards imprisoned by Demetrius Soter (B.C. cir. 158). The termination ( Tissaphernes , etc.) points to a Persian origin, but the meaning of the word is uncertain. Smith. See Volkmar, Einleitung In Die Apokryphen (Tub. 1860-3), 1, 179 sq.; Graitz, Geschichte Der Juden, 4, 455. According to the account in the book of Judith, Nebuchadnezzar, "king of Nineveh," having resolved to "avenge himself on all the earth," appointed Holofernes general of the expedition intended for this purpose, consisting of 120,000 foot and 12,000 horse. Holofernes marched westward and southward, carrying devastation everywhere he came, destroying harvests, and flocks, and cities, as well as men, old and young; making even the "cities of the sea-coast," which had submitted to him, feel the weight of his arm. Having reached Esdraelon, he encamped "between Geba and Scythopolis" a whole month to collect his forces. The Jews, however, resolved to resist him, and fortified all the mountain passes. Dissuaded by Achior, "captain of the sons of Ammon," from attacking the Jews, he resented the advice and delivered Achior into the hands of the Jews in Bethulia, from whom, however, he met with a kind reception. Holofernes proceeded against Bethulia (q.v.) where he was brought to bay; and, instead of attacking it, seized upon two wells on which the city depended for water, and sat down before it to take it by siege. While here he fell a victim to the treachery of Judith, a beautiful Jewish widow, who artfully managed to be brought into his presence, and who, by playing the hypocrite, secured his favor and confidence. Having invited her to a banquet, he drank freely, and, having fallen asleep, fell beneath the arm of his fair guest, who cut off his head with his own sword, and escaped with her bloody trophy to her own people in Bethulia. The Jews immediately fell on their enemies, who, finding their general dead in his tent, fled in confusion. Such is the story. It is scarcely necessary to add that it is wholly unhistorical. Kitto. (See Judith).

International Standard Bible Encyclopedia [4]

hol - ō̇ - fûr´nēz ( Ὀλοφέρνης , Olophérnēs ): According to the Book of Judith, chief captain of Nebuchadnezzar, king of the Assyrians (  Judith 2:4 ), who was commissioned to make war upon the West country and to receive from the inhabitants the usual tokens of complete submission, earth and water. The object of the expedition of Holofernes, who thus became the typical persecutor of the Jews, was to compel men everywhere to worship Nebuchadnezzar. He was slain by Judith, the heroine of the book of that name, during the siege of Bethulia. There is no notice of Holofernes except in the Book of Judith. The termination of the word would seem to indicate a Persian origin for the name. The Holofernes of Shakespeare and Rabelais is in no way connected with the deeds of the Holofernes of the Apocrypha.

The Nuttall Encyclopedia [5]

The Assyrian general whom the Jewish Judith, entering his camp as it invested her native place, slew with her own hand, and bore his head as a trophy back to the town.