From Greek mythology to modern horror and fantasy, literature is full of fantastic beasts and terrifying monsters. What makes a great fictional monster? Terror, unpredictability, and perhaps an unsettling commingling of the familiar with the unfamiliar? These qualities can all help to create a truly scary monster which haunts our dreams, even though we know it doesn’t actually exist. Here are ten of our favourite horrifying monsters from the world of classic fiction, myth, and epic poetry. Thankfully, none of these monsters have ever existed. Phew!
The Minotaur from Greek mythology. The tale of the Minotaur – the creature that was a man with the head of a bull – is well-known. The Minotaur was created by Daedalus (father of Icarus) to guard the Labyrinth on the Greek isle of Crete. The Greek hero Theseus famously slew the Minotaur, and was able to find his way back out of the Labyrinth thanks to a ball of thread that Ariadne had provided him with. There is something about the combination of man with bull (especially the bull’s head, with its horns so effective in the act of butting an enemy) concealed in a dark maze that exercises a monstrous power over the imagination, so the Minotaur seems a great place to begin our rundown of great fictional monsters.
Scylla from Homer’s Odyssey. Usually paired with Charybdis (which was the name given to a nearby whirlpool) and depicted with six monstrous dog heads in Homer’s Odyssey, Scylla is a mythic sea monster that appears in the Odyssey as well as Virgil’s later Aeneid. Scylla and Charybdis both lurk in the sea, only a short distance from each other, meaning that any ship trying to avoid the whirlpool that is Charybdis risks sailing into the jaws of Scylla (and similarly, any mariner avoiding becoming Scylla’s lunch could end up being sucked into the whirling vortex of Charybdis). The legend of Scylla has long been associated with the Strait of Messina between Calabria in Southern Italy, and the island of Sicily, and may have arisen from the sharp black coral found in that part of the Mediterranean, near the cave where Scylla was said to dwell.
The Kraken from Norse mythology. Another sea monster, this time from Nordic mythology rather than Greek, the Kraken resembles a gigantic octopus that terrorised the north Atlantic according to Nordic folklore. The Kraken was made more familiar to an English audience thanks to Tennyson’s famous poem about the monster.
Grendel from Beowulf. Grendel is actually only one of three monsters the hero of this anonymous Anglo-Saxon poem has to fight: once Beowulf is done with Grendel, he has to fight the monster’s mother, and then, at the climax of the poem, a dragon. In a classic fantasy novella, John Gardner told Grendel’s side of things, making a far more sympathetic character out of the monster than we find in the 
original poem. It’s hard to describe what Grendel actually is, since the original poem doesn’t describe his features in clear detail. However, he’s usually assumed to be some sort of giant.
The Blatant Beast from The Faerie Queene. The word ‘blatant’ comes from Spenser’s epic poem: the ‘Blatant Beast’ is a monster that is the personification of the calumnious voice of the world, begotten of Envy and Detraction, and described as having a thousand tongues. One of the things which make the monsters of Spenser’s vast poem so interesting is their allegorical meaning: they all stand for some vice against which our virtuous protagonists are fighting or whose wiles they are trying to resist.
The Creature from Frankenstein. Although the phrase ‘Frankenstein’s Monster’ has entered common parlance, it’s a rather unsympathetic way to describe the Creature from Mary Shelley’s novel (and it’s been recently suggested that ‘Being’ may even be a preferable word). Nevertheless, numerous film adaptations over the last century – and Frankenstein is one of the most widely adapted literary works ever written – have embedded Boris Karloff’s green-faced monster in the common consciousness, so he has to feature in a list of fictional ‘monsters’.
Dracula from … Dracula. Dracula needs little introduction, although it’s worth pointing out that vampire fiction in Britain was well-established by the time the Irish-born Bram Stoker published his famous novel in 1897. Dracula, however, was a richer and more complex creation than most, fusing the history of the fifteenth-century ruler Vlad the Impaler with folklore and contemporary fears surrounding ‘the Other’ as the nineteenth century drew to a close. Seen by Jonathan Harker climbing the walls of his castle in Transylvania, Dracula can transform himself into bat and human at will.
The Beetle from The Beetle. Another fictional shape-shifter who made their debut in print in 1897, the Beetle is a female entity, born of the cult of Isis (no relation), who can be both beetle and human, and who arrives in the city of London hell-bent on exacting a terrible revenge upon a British politician. The Beetle, written by ‘Richard Marsh’, was initially more popular than Stoker’s creation when it was published in 1897, although that soon changed, and the novel was long-forgotten and out of print. Now it’s readily available again, and well worth reading, not least for its horrific title character.
Smaug from The Hobbit. Let’s conclude with a couple of the best-known monsters from Tolkien’s Middle-Earth. Smaug is the dragon that guards the hoard of treasure that Bilbo Baggins, and the party of dwarves, go off in search of in Tolkien’s original story, The Hobbit (1937). Drawing on his intensive knowledge of Nordic folklore, Tolkien made a children’s story (that also stands up to being reread in adulthood) out of centuries-old legend. We had to include one dragon on this list, and although this one may not be the most fearsome dragon in all of literature and myth, Smaug has become one of the most famous.
The Balrog from The Lord of the Rings. We’ll conclude this list of fictional monsters with another from Tolkien’s work: the Balrog, the tall, fearsome being with fiery whip-like tentacles. A Balrog carries Gandalf down into the depths in the Mines of Moria in The Lord of the Rings, although other Balrogs turn up in The Silmarillion, Tolkien’s life’s work which builds up the mythology of Middle-Earth. The prospect of being caught up in a creature’s tentacles is bad enough, but when those tentacles seem to be made of pure fire, the thought is even more terror-inducing.