In the Old Testament, Amraphel (Hebrew: אַמְרָפֶ֣ל ’Amrāp̄el) was a king of Shinar (Sumer) in Genesis xiv.1 and 9, who invaded the west along with Chedorlaomer, king of Elam, and others, and defeated Sodom and the other Cities of the Plain in the Battle of the Vale of Siddim.
Beginning with E. Schrader (Cuneiform Inscriptions and the Old Testament, vol II (1888), pp 299ff) this king was usually associated with Hammurabi, who ruled Babylonia from 1792 BC until his death in 1750 BC. However, according to The Oxford Companion to the Bible, this view has been largely abandoned in recent years. In Hammurabi's time, the entire former region of Sumer had come to be named Babylonia after the city of Babylon. However, the account of Abraham in Genesis takes place at a time when Amraphel is identified as a king of Shinar, not "Babylonia" — although Babel had previously (ch. 10-11) been mentioned as one of the locations within Shinar.
In past centuries, it was fashionable to identify Amraphel with Aralius, one of the names on the later Babylonian king-lists, attributed first to Ctesias. According to John Van Seters in Abraham in History and Tradition, the existence of Amraphel is unconfirmed by any sources outside the Bible.
Rabbinic sources such as Midrash Tanhuma Lekh Lekhah 6, Targum Yonatan to Ex. 14:1, and Eruvin 53a and identify Amraphel with Nimrod. This is also asserted in the 11th Chapter of the Sefer haYashar (Book of Jasher), attested from the early 17th century:
"And Nimrod dwelt in Babel, and he there renewed his reign over the rest of his subjects, and he reigned securely, and the subjects and princes of Nimrod called his name Amraphel, saying that at the tower his princes and men fell through his means. - Book of the Upright (Jasher) 11
Genesis Rabbah 42 says Amraphel was called by three names: Cush, after his father's name (Gen. 10:8), Nimrod, because he established rebellion (mrd) in the world, and Amraphel, as he declared (amar) "I will cast down" (apilah).