Re'em

A beast mentioned nine times in the Bible (Job 39:9,10, Deuteronomy 33:17, Numbers 23:22 and 24:8; Psalm 22:21, 29:6 and 92:10; and Isaiah 34:7), translated to unicorn in the King James version of the Bible. It is translated as "wild ox" in the NASB. Also speculated to refer to the Arabian Oryx or the extinct aurochs. Some Creationists believe it to be a ceratopsid.

"Will the unicorn be willing to serve thee, or abide by thy crib? Canst thou bind the unicorn with band in the furrow? or will he harrow the valleys after thee? Wilt thou trust him, because his strength is great? or wilt thou leave thy labour to him? Wilt thou believe him, that he will bring home thy seed, and gather it into thy barn?" (Book of Job 39:9–12 trans. KJV)}

The Book of Job is thought by many to be the oldest book in the Bible. Other mentions include Deuteronomy 33:17, Numbers 23:22 and 24:8; Psalm 22:21, 29:6 and 92:10; and Isaiah 34:7.

The word may be related to the Akkadian "rimu", which means, "wild ox", which would add credence to the idea that it was originally the aurochs. [1]

In the Harry Potter universe of JK Rowling, Re'em are described as "extremely rare giant oxen with golden hides," whose blood bestows great strength on anyone who drinks it. (Fantastic Beasts and Where to Find Them p. 36)