The Bible makes frequent mention of a horned animal called a r’em, often invoked as symbol of might or majesty. Following the Greek Septuagint and the Latin Vulgate, which render the word as monoceros and unicornis, respectively, the King James Bible translates it as “unicorn.” Other translations include wild ox, buffalo, and rhinoceros, but there is reason to think that the r’em is in fact an oryx, found in Israel’s deserts since ancient times. Amit Naor speculates that this beast may be the inspiration for legends of unicorns, and certainly for the reports of unicorn sightings in the Land of Israel:
The oryx is a type of large antelope; there are several different species of oryx living around Africa and the Middle East. The kind found in Israel and the surrounding countries is the white or Arabian oryx, its coat mostly white, with two long, straight horns on its head.
Wait a minute—two horns? . . . Bear with me.
[I]n one of the first [printed] books containing an account of a journey to the Holy Land, composed by the German traveler Bernhard von Breydenbach around 1485, we find an illustration of various animals he spotted during his travels. Breydenbach traveled from Venice to Jaffa, making his way to Jerusalem before later heading south to the Sinai desert. The illustration shows a number of exotic animals including a camel, a crocodile, a goat, a salamander, and—a unicorn. Breydenbach wrote that he got a brief glimpse of one in the Sinai.
According to one theory, the oryx’s long, straight horns may appear as a single horn if the animal is viewed from the side. A viewer who is only able to get a quick glimpse from such an angle might mistake the oryx for a large horse with a single horn. . . . [A]nother theory suggests that the stories are based on oryxes who lost one of their horns at some point, as these protrusions never grow back.
Read more on The Librarians: https://blog.nli.org.il/en/hoi_unicorns