Aquila (Hebrew: עֲקִילַס ‘áqīlas, fl. 130 AD) of Sinope (modern-day Sinop, Turkey; Latin: Aquila Ponticus) was a translator of the Old Testament into Greek, proselyte, and disciple of Rabbi Akiva, sometimes assumed to be one and the same as Onkelos.
Only fragments of this translation have survived in what remains of fragmentary documents taken from the Books of Kings and the Psalms found in the old Cairo Geniza in Fustat, Egypt, while excerpts taken from the Hexapla written in the glosses of certain manuscripts of the Septuagint were collected earlier and published by Frederick Field in his momentous work, Origenis Hexaplorum quæ Supersunt, Oxford, 1875. Epiphanius' De Ponderibus et Mensuris (chap. xiii-xvi.; ed. Migne, ii. 259-264) preserves a tradition that he was a kinsman of the Roman emperor Hadrian, who employed him in rebuilding Jerusalem as Aelia Capitolina, and that Aquila was converted to Christianity but, on being reproved for practicing astrology, 'apostatized' to Judaism. He is said also to have been a disciple of Rabbi Akiva (d. ca. 132 CE). 
In Jewish writings he is referred to as עקילס (Aquilas) and אונקלוס (Onkelos). Aquila's version is said to have been used in place of the Septuagint in Greek-speaking synagogues. The Christians generally disliked it, alleging that it rendered the Messianic passages incorrectly, but Jerome and Origen speak in its praise. Origen incorporated it in his Hexapla.
It was thought[who?] that the Hexapla were the only extant fragments of the work, but in 1897 fragments of two codices were brought to the Cambridge University Library. These have been published: the fragments AqBurkitt containing 1 Kings xx. 7-17; 2 Kings xxiii. 12-27 by Francis Crawford Burkitt in 1897, those containing parts of Psalms xc.-ciii. (signed as AqTaylor) by C. Taylor in 1899. See F. C. Burkitt's article in the Jewish Encyclopaedia.
The surviving fragments of this translation, and of other Greek translations forming part of Origen's Hexapla, are now being re-published (with additional materials discovered since Field's edition) by an international group of Septuagint scholars. This work is being carried out as The Hexapla Project  under the auspices of the International Organization for Septuagint and Cognate Studies, and directed by Peter J. Gentry (Southern Baptist Theological Seminary), Alison G. Salvesen (University of Oxford), and Bas ter Haar Romeny (Leiden University).
The leading Aramaic Targum (translation) of the Pentateuch, as appended to most printed Hebrew texts of the Five Books of Moses, is known as Targum Onkelos. The names "Onkelos the proselyte" and "Aquilas the proselyte" are used interchangeably between the Babylonian Talmud and Jerusalem Talmud, with the reference being to the same person. It is not clear how much (if any) of the Aramaic translation was based on the Greek.
Early Rabbinic reference to Aquila's conversion
Once, Aquilas said to Hadrian the king, ‘I wish to convert and to become one of Israel.’ He answered him, ‘You are seeking [to join] that nation? How have I despised it! How have I killed it; the most downtrodden of the nations you are asking to join!? What have you seen in them that you wish to be made a proselyte?’ He replied, ‘The smallest of them knows how the Holy One, blessed be He, created the universe; what was created on the first day and what was created on the second day, and how many [years] have passed since the universe was created, and by what [things] the world is sustained. Moreover, their Divine Law is the truth.’ He said to him, ‘Go and study their Divine Law, but do not be circumcised.’ Aquilas then said to him, ‘Even the wisest man in your kingdom, and an elder who is aged one-hundred, cannot study their Divine Law if he is not circumcised, for thus is it written: He makes known his words unto Jacob, even his precepts and judgments unto Israel. He has not done the like of which to any other nation, (Ps. 147:19-20). Unto whom, then, [has he done it]? Unto the sons of Israel!’
- Chambers Biographical Dictionary. London: Credo Reference. 2011. Aquila.
- Würthwein, Ernst (1995-01-01). The Text of the Old Testament: An Introduction to the Biblia Hebraica. Wm. B. Eerdmans Publishing. p. 55. ISBN 9780802807885. Cf. Jenny R. Labendz, "Aquila's Bible Translation in Late Antiquity: Jewish and Christian Perspectives," The Harvard Theological Review, Vol. 102, No. 3 (Jul., 2009), pp. 353-388: "Owing in large part to A. E. Silverstone's 1931 study, Aquila and Onkelos, scholars have long accepted the notion that Aquila is identical to Onkelos, a character mentioned numerous times in the Tosefta and to whom the Aramaic Bible translation is attributed in the Babylonian Talmud. However, there is no basis for this claim. As early as 1937, Leon Leibrich published a review of Silverstone's book that pointed to flaws in his logic, textual analysis, and assumptions, as well as to blatant inaccuracies in the work. Based on Leibrich's review and other points that space does not permit me to delineate here, it is clear to me that Onkelos bears no relation to Aquila...Moreover, already in the sixteenth century, the Italian scholar Azariah de Rossi set out to clear up this confusion and prove that the two were not the same. Sefer me 'or eynayim (ed. David Cassei; Vilna: 1866) 383-93 (Imre vinah, ch. 45); English translation in The Light of the Eyes: Azariah de' Rossi (ed. Joanna Weinberg; New Haven, Conn.: Yale University Press, 2001) 571-85"
- Epiphanius' "Treatise on Weights and Measures" - Syriac Version (ed. James Elmer Dean), Chicago University Press c1935, pp. 30-31. Click to see online translation of Epiphanius' Treatise on Weights and Measures
- Chisholm 1911.
- Website of the Hexapla Project
- Website of the International Organization for Septuagint and Cognate Studies
- Cf. Jerusalem Talmud, Megillah 10b (Commentary Korban Ha-Edah, ibid.) and Babylonian Talmud, Megillah 3a; Epiphanius' Treatise on Weights and Measures (Syriac version), ed. James Elmer Dean, Chicago University Press: Chicago 1935, p. 30