Variations: Katthvalur, Kettuhvalur; Kattfiskur (Cat-fish); Kisa (Kitty); Bísill (Feline); Sea-cat


The Katthveli (“Cat-whale”), is one of Iceland’s many evil whales or “illhveli”. It is generally smaller and of a less harmful nature than its larger brethren, and has even been tamed on occasion. As with other illhveli, it is inedible and will zero in on anyone who mentions its name. Speaking about it at sea is considered highly foolish.

The katthveli has been described as a seal, dolphin, or whale with bulky forequarters and narrower hindquarters, with the mouth of a leopard, the strength of a lion, and the hunger of a hound. It earns its name from the long, furzy whiskers on its snout and the sounds it makes, ranging from a purr when it exhales to mews and hisses when agitated. It is fairly small and kittenish at 16 cubits (8 meters), with a short rounded head with nodules that resemble ears. It has short, sharp teeth protruding from its upper jaw, and Saint Brendan adds that it has boar’s tusks. The eyes gleam brazenly. The flippers are large, and nasty hooked claws are present. Known colors include pink, grey, peaty brown, and countershaded; the one encountered near the Faroe Islands was pale under the chin and had woolly skin.

Katthvelis have been known to school with rorquals and large fish. These whales are cruel and vicious, using their speed and agility to swim underneath boats and flip them. One katthveli chased a boat off the Skálanesbjarg cliffs, but gave up after it was outsped by the rowers. Another one intercepted a ship at Héradsflói and remained alongside it, preventing the sailors from fishing and following them with its eyes. Harpooning it was ruled out as nobody wanted to provoke it, and it eventually dove and disappeared by nightfall. Ásmundur Helgason and his companions were attacked by one off Seley Island; it rammed their boat and stuck its head through the hull. After a terrifying struggle, they managed to push it out and make for safety despite the damage. A Faroese katthveli at Suðuroy reared out of the water and put its flippers on the gunwale of a boat, hissing and spitting like a cat and snapping at the sailors until one quick-thinking man put his gun in its mouth and fired, whereupon it slid off into the depths.

St. Brendan encountered a “sea-cat” the size of a horse on a small island. It had originally been brought as a pup along with twelve pilgrim sailors, and was quite friendly and tame, but soon grew bigger and hungrier and eventually ate all but one of the sailors, who took refuge in a small stone church. St. Brendan prayed for aid, and immediately a great whale lunged out of the sea and seized the sea-cat, pulling it into the sea where they both drowned each other.

The wolffish Anarhichas lupus was also known colloquially as the cat-fish or sea-cat in older English, and may be associated with the katthveli. If it was born from mistaken identity, a large seal such as the walrus or bearded seal is a more plausible contender.


Cunningham, J. T. (1896) The Natural History of the Marketable Marine Fishes of the British Islands. MacMillan and Co., London.

Joensen, J. P. Tradition and Changes in the Concepts of Water-Beings in Faroese Folklore. In  Lysaght, P.; Ó Catháin, S.; and Ó hÓgáin, D. (1996) Islanders and Water-Dwellers. Proceedings of the Celtic-Nordic-Baltic Folklore Symposium, DBA Publications, Dublin.

Hlidberg, J. B. and Aegisson, S.; McQueen, F. J. M. and Kjartansson, R., trans. (2011) Meeting with Monsters. JPV utgafa, Reykjavik.

Stokes, W. S. (1890) Lives of Saints from the Book of Lismore. Clarendon Press, Oxford.