Does the Bible teach that unicorns and other such mythical animals actually exist? Short answer: no. I shall argue that polemical charges to the contrary are misguided and wrongheaded.

Unfortunately, the word “unicorn” appears in the King James Version (note that translations are not the Bible itself, and not infallible) nine times (Numbers 23:22; 24:8; Deuteronomy 33:17; Job 39:9,10; Psalms 22:21; 29:6; 92:10; Isaiah 34:7). But even the secular editors of the Encyclopaedia Britannica wrote:

Certain poetical passages of the biblical Old Testament refer to a strong and splendid horned animal called re’em. 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 re’em (1997, vol. 12:129).

Apostate atheist John W. Loftus, in his book, Why I Became an Atheist (revised version, Prometheus: 2012, p. 263) poked fun of the supposed literal biblical belief in “Satyrs — creatures that were half man and half goat or horse (Isaiah 13:31)” .

The Hebrew word sa‘ir appears about 52 times in the Old Testament. It’s linguistically related to the term se‘ar (hair), and is used, for example, to speak of the male goat used as a sin offering on the Day of Atonement (Lev 16:5, 7-10, 15, 18, 20-22).

For some reason the 1611 King James Version rendered sa‘ir as “satyr” twice (Isaiah 13:21; 34:14). The surrounding contexts, however, prove that it is again referring to wild goats. Isaiah 13:21-22 (RSV) makes reference to wild beasts, howling creatures, hyenas, and jackals (all real animals: last time I checked). Goats fit right in with this “zoo.” Likewise, 34:11, 13-15 mentions hawks, porcupines, owls, ravens, jackals, ostriches, wild beasts, and hyenas.

Loftus brings up “Leviathan” (p. 262) and “Behemoth” (p. 263) and taunts on the next page: “how can God defeat mythical beasts that do not exist?” According to New Bible Dictionary (edited by J. D. Douglas, Grand Rapids, Michigan: Eerdmans Pub. Co., 1962), Leviathan in Psalms 104:26 is “generally thought to be the whale.” In Job 41:1-34, “most scholars” think it is a “crocodile” (p. 729 for both citations). In other instances, the use is clearly symbolic. Smith’s Bible Dictionary (London and Boston: 1863) essentially concurs:

The crocodile is most clearly the animal denoted by the Hebrew word. . . . The context of Psalms 104:26 seems to show that in this passage the name represents some animal of the whale tribe, which is common in the Mediterranean; but it is somewhat uncertain what animal is denoted in Isaiah 27:1. As the term leviathan is evidently used in no limited sense, it is not improbable that the “leviathan the piercing serpent,” or “leviathan the crooked serpent,” may denote some species of the great rock-snakes which are common in south and west Africa.

New Bible Dictionary on “Behemoth” states that “in all but one of these [nine] occurrences ‘beasts’, ‘animals’, or ‘cattle’ is apparently the intended meaning.” In Job 40:15, “the hippopotamus . . . seems to fit the description best” (p. 138). The Catholic Encyclopedia (“Animals in the Bible”) agrees:

...generally translated by “great beasts”; in its wider signification it includes all mammals living on earth, but in the stricter sense is applied to domesticated quadrupeds at large. However in Job 40:10, where it is left untranslated and considered as a proper name, it indicates a particular animal. The description of this animal has long puzzled the commentators. Many of them now admit that it represents the hippopotamus, so well known to the ancient Egyptians; it might possibly correspond as well to the rhinoceros.

We need not posit an interpretation of mythical animals in any of these passages. Loftus notes that the Bible references “dragons” (p. 263). Smith’s Bible Dictionary states concerning this:

The translators of the Authorized Version, apparently following the Vulgate, have rendered by the same word “dragon” the two Hebrew words tan and tannin, which appear to be quite distinct in meaning....

The word tannin seems to refer to any great monster, whether of the land or the sea, being indeed more usually applied to some kind of serpent or reptile, but not exclusively restricted to that sense. [Exodus 7:9-10, 12; 32:33; Psalm 91:13].

The Catholic Encyclopedia (ibid.) elaborates:

tánnîm, in a few passages with the sense of serpent [Deuteronomy 32:33; Psalm 90:13; Daniel 14:22-27), in others most likely signifying the crocodile [Psalm 73:13; Isaiah 51:9; Ezekiel 29:3], or even a sea-monster (Ezekiel 32:2), such as a whale, porpoise, or dugong, as rightly translated Lamentations 4:3, and as probably intended Psalm 148:7...

Of the fabulous dragon fancied by the ancients, represented as a monstrous winged serpent, with a crested head and enormous claws, and regarded as very powerful and ferocious, no mention whatever is to be found in the Bible.

Loftus brings up (p. 263) another mythical creature, the cockatrice. The King James Version mentions it at Isaiah 11:8 and 14:29, and Jeremiah 8:17, but modern translations usually render the Hebrew, Tsepha, or Tsiphoni, as cobra or asp (Isaiah 11:8), and viper/poisonous snake/adder (Isaiah 14:29). 

Loftus also mentions “Fiery serpents (Deuteronomy 8:15), and Flying serpents (Isaiah 30:6)” (p. 263). Wikipedia has an excellent article, “Fiery flying serpent” which identifies this animal as:

the Israeli saw-scale viper or carpet viper (Echis coloratus) based on ten clues from the written sources: the serpents . . . are deadly poisonous, extremely dangerous, especially painful “fiery” bite, reddish “fiery” color, lightning fast strike, leaping/”flying” strike, and death by internal bleeding.

Meanwhile, Roman naturalist philosopher Pliny the Elder (AD 23–79) literally believed in legendary creatures such as the manticore, basilisk, catoblepas, phoenix, and werewolf. Herodotus, Ovid, and Virgil wrote seriously about werewolves. 

Loftus concludes: “What we find in the Bible is just more of the same” (p. 263). Not quite. The ancient Hebrews (unlike the “sophisticated” pagan Greeks and Romans) did not believe in mythical animals, as has just been demonstrated.