Certain poetical passages of the biblical Old Testament refer to a strong and splendid horned animal called reʾem. This word was translated “unicorn” or “rhinoceros” in many versions of the Bible, but many modern translations prefer “wild ox” (aurochs), which is the correct meaning of the Hebrew reʾem. As a biblical animal the unicorn was interpreted allegorically in the early Christian church. One of the earliest such interpretations appears in the ancient Greek bestiary known as the Physiologus, which states that the unicorn is a strong, fierce animal that can be caught only if a virgin maiden is thrown before it. The unicorn leaps into the virgin's lap, and she suckles it and leads it to the king's palace. Medieval writers thus likened the unicorn to Christ, who raised up a horn of salvation for mankind and dwelt in the womb of the Virgin Mary. Other legends tell of the unicorn's combat with the elephant, whom it finally spears to death with its horn, and of the unicorn's purifying of poisoned waters with its horn so that other animals may drink.

Cups reputedly made of unicorn horn but actually made of rhinoceros horn or narwhal tusk were highly valued by important persons in the Middle Ages as a protection against poisoned drinks. Many fine representations of the hunt of the unicorn survive in medieval art, not only in Europe but also in the Islāmic world and in China.