From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Dositheus . 1. The priest who, according to a note in one of the Greek recensions of Esther, brought the book to Alexandria in the 4th year of Ptolemy Philometor (?) and Cleopatra, c [Note: circa, about.] . b.c. 178 (Ad. Est 11:1). 2. A soldier of Judas Maccabæus, who made a vain attempt to take Gorgias prisoner ( 2Ma 12:35 ). 3. A renegade Jew who frustrated the plot of Theodotus to assassinate king Ptolemy Philopator ( 3M  Malachi 1:3 ). 4. An officer of Judas Maccabæus ( 2Ma 12:19; 2Ma 12:24 ).

Smith's Bible Dictionary [2]

Dosith'eus. A "priest and Levite," who carried the translation of Esther to Egypt.  Esther 11:1-2 Apocrypha.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [3]

a Samaritan, in the first century, who claimed to be Messiah, or the prophet promised in  Deuteronomy 18:18. The Church fathers ascribe to him peculiarly many doctrines which had always been held by the Samaritans. He was chiefly distinguished by an ascetic life, and an over-scrupulous observance of the Sabbath (Origen, De princ. 4, c. 17: Quo quisque corporis situ in principio sabbathi inventus fuerit, in eo ad vesperum usque ipsi permanendum esse), which originated evidently in a verbal interpretation of  Exodus 16:29. As late as the year 588 the followers of Dositheus were engaged in a controversy with the other Samaritans concerning the passage,  Deuteronomy 18:18 (Eulogius Ap. Phot. Bibl. Cod. page 230; Gieseler, Ch. History, 1, 18). Instead of being included in the class of heretics, he ought to be classed among those lunatics who have fancied themselves divine messengers. His impious claims caused an order from the Samaritan high-priest for his apprehension; and Dositheus took refuge in a cave, where he is said to have starved to death (Epiphanius, Hares. 13, cited by Mosheim, Hist. Comment. N.Y. 1851, 1:240 note).

International Standard Bible Encyclopedia [4]

dō̇ - sith´ē̇ - us ( Δοσίθεος , Dosı́theos ):

(1) A captain of Judas Maccabeus (2 Macc 12:19-25); along with Sosipater he captured Timotheus after the battle of Carnion, but granted him his life and freedom on the representation that "he had in his power the parents of many of them and the brethren of some," who, if they put him to death, should "be disregarded."

(2) A soldier in the army of Judas Maccabeus (2 Macc 12:35); he made a special attack upon Gorgias, governor of Idumaea, the opposing general, and would have taken the "accursed man" prisoner but for the interference of a Thracian horseman.

(3) A J ew, son of Drimylus (3 Macc 1:3) who rescued Ptolemy Philopator from a plot of Theodotus. He afterward proved an apostate from Judaism.

(4) A L evite priest who "in the 4th year of the reign of Ptolemy and Cleopatra" carried the translation of the Book of Esther to Alexandria (Additions to Esther 11:1).