From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

Osnappar (so written in RV [Note: Revised Version.] of   Ezra 4:10 . Asnapper of AV [Note: Authorized Version.] is more correct; but the best reading of the Hebrew is Asenappar ). A curiously distorted form of Ashurbanipal , the name of the last great king of Assyria (b.c. 668 626), the son of Esarhaddon, and grandson of Sennacherib. He is distinguished chiefly as the great conserver of the ancient Babylonian literature, whose rich and varied collections have come to us from his own library in Nineveh. He succeeded by great efforts in keeping together the empire of his father; and he added thereto the country of Elam in a fierce campaign which ended with the capture of Susa (Shushan), about b.c. 645. It was after this event that the deportation, alluded to in   Ezra 4:9-10 , of ‘Shushanchites’ and Elamites’ to Samaria and the vicinity took place. The war against Elam was the conclusion of a great conflict with Babylonia, with which country Elam on the east and most of the western subject States, including Judah, were in alliance. And it was before Ashurbanipal, as victorious king of Babylonia, that the rebel Judahite Manassch was brought in fetters to Babylonia, as related in   2 Chronicles 33:11 an event whose historicity has been unnecessarily called in question.

J. F. M‘Curdy.