From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Lysimachus 1 . The translator of the Greek edition of Esther into Greek (Ad. Est 11:1). 2 . The brother of the high priest Menelaus. He excited the hatred of the populace by his systematic plundering of the Temple treasures, and was finally killed in a riot ( 2Ma 4:28; 2Ma 4:39-42 ).

Smith's Bible Dictionary [2]

Lysim'achus. "A son of Ptolemaeus of Jerusalem," the Greek translator of the book of Esther. Compare  Esther 9:20.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [3]

( Λυσίμαχος , a frequent Greek name), the name of two men mentioned in the Apocrypha.

1. "The son of Ptolemneus of Jerusalem," commonly supposed to be the translator into Greek of the Book of Esther (see the close of the Sept. version). The Apocryphal "rest of the Book of Esther," A.V., says, "In the fourth year of the reign of Ptolemneus and Cleopatra, Dositheus, who said he was a priest and Levite, and Ptolemus his son, brought this epistle of Phurim, which they said was the same, and that Lysimachus, the son of Ptolemeulls, that was at Jerusalem, had interpreted it" (11:1). There is, however, no reason to suppose that the translator was also the author of the additions made to the Hebrew text. (See Apocryphal Additions To Esther).

2. A brother of the Menelaus whom Antiochus appointed high-priest (B.C. cir. 171). Menelaus left him temporarily "in his stead in the priesthood," and encouraged him to commit many sacrileges. Thus he roused the indignation of the common people, who rose against him and killed him ( 2 Maccabees 4:29;  2 Maccabees 4:39). The Vulgate erroneously makes him the successor instead of the deputy of Menelaus.

International Standard Bible Encyclopedia [4]

lı̄ - sim´a - kus ( Λυσίμαχος , Lusı́machos ):

(1) The son of Ptolemy, of Jerusalem, is named (Additions to  Esther 11:1 ) as the interpreter (translator of the Rest of Esther into Greek). See Esther , The Rest Of .

(2) Brother of Menelaus, a Greek name said by Josephus ( Ant. , Xii , v, 1) to have been assumed by Onias, the high priest in the hellenizing days of Antiochus Epiphanes, as the Jewish name Jesus was changed to Jason. When Menelaus was summoned to Antioch ( 2 Maccabees 4:29 ) on a charge of malversation, he left Lysimachus as his deputy in the priesthood at Jerusalem. Lysimachus robbed the temple and caused an insurrection in which he met his death beside the treasury ( 2 Maccabees 4:42 ). The name of Lysimachus does not appear in the narrative of these events given by Josephus

The Nuttall Encyclopedia [5]

One of the generals of Alexander the Great, who became king of Thrace and afterwards of Macedonia; d . 281 B.C.