The kraken is a mythological sea monster from Norway who features in legends from other Scandinavian countries as well. According to myth, krakens favor the waters off the coast of Norway and Iceland, although it is also possible to find stories about krakens or similar sea monsters who appear in other parts of the world. Some authors also found the tale of the kraken compelling enough to borrow it; H.P. Lovecraft, for example, wrote about a version of the kraken known as Cthulu. The kraken also appears in poetry and literature by authors like Tennyson, Verne, and Tolkien, among others.

Numerous fairy tales and paintings depict the kraken, usually as a many-armed monster similar to an octopus or squid. In all myths, the kraken is much larger than ordinary versions of these animals, although descriptions of its size vary. In some tales, the kraken could reach with ease to the top of a ship's masts, and it others it was so gigantic that its body could be mistaken for an island. Some stories about the kraken actually describe ships anchoring next to the creature, ignorant to the danger.

In all stories, the kraken is a bloodthirsty creature which cracks ships open and devours the crew along with various sundries on board. The armed versions of the kraken could grip ships and manipulate them in the water with the assistance of their tentacles, while versions which took the form of giant crabs and lobsters could crack ships apart with their formidable claws. In any case, the kraken was not a creature which one wanted to run into.

In most myths, the kraken prefers to lurk in the depths of the water, only periodically coming to the surface. Krakens surface when they are hungry or disturbed, as might be the case when a large ship sails or fishes overhead. The stories about the kraken would certainly have explained why many ships failed to return home in historical eras when seafaring was extremely dangerous.

Some historians have suggested that the myth of the kraken may be based in actual fact. There are giant versions of both squid and octopi, and it is possible that seafarers encountered these creatures in their travels, and perhaps exaggerated their size and ferocity. Krakens were actually categorized at one point by Linnaeus, the father of modern taxonomy, although later editions of Linnaeus' work lacked descriptions and classifications for krakens.