Targum Onkelos (or Unkelus) is the official eastern (Babylonian) targum (Aramaic translation) to the Torah. However, its early origins may have been western, in Israel. Its authorship is attributed to Onkelos, a famous convert to Judaism in Tannaic times (c. 35–120 CE).
According to Jewish tradition, the content of Targum Onkelos was originally conveyed by God to Moses at Mount Sinai. However, it was later forgotten by the masses, and rerecorded by Onkelos.
Some identify this translation as the work of Aquila of Sinope in an Aramaic translation (Zvi Hirsch Chajes), or believe that the name "Onkelos" originally referred to Aquila but was applied in error to the Aramaic instead of the Greek translation. The translator is unique in that he avoids any type of personification. Samuel D. Luzzatto suggests that the translation was originally meant for the "simple people". This view was strongly rebutted by Nathan Marcus Adler in his introduction to Netinah La-Ger. In Talmudic times, and to this day in Yemenite Jewish communities, Targum Onkelos was recited by heart as a verse-by-verse translation alternately with the Hebrew verses of the Torah in the synagogue.
The Talmud states that "a person should complete his portions of scripture along with the community, reading the scripture twice and the targum once (Shnayim mikra ve-echad targum)." This passage is taken by many to refer to Targum Onkelos.