Krith are giant spiders that glide through space on membraneous wings. They unfold space, emerging from cracks, fissures, and anomalies in spacetime when they sense the proximity of intelligent quarry. They have also been encountered emerging from black gates and otherwise apparently inactive hyperspace nodes
After entering normal space, krith move rapidly toward their prey. They don't cast true physical webs, instead entangling their targets within hypersnares: unstable, magnetically and gravitically "sticky" tangles of chaotic spacetime. Ships attacked by these creatures suffer drive accidents and other sudden and disastrous systems excursions.
Krith are able to phase their way inside of most ship hulls to prey directly on crew. The only hulls with protection against krith incursions are found on a handful of ancient vessels manufactured during the Archaic Oikumene. These ships have ceramic hulls incorporating various types of exotic matter.
Interestingly, the spaceborn Voidgliders have many legends about these creatures, and some among their kind claim to know ways to call the space spiders out of the void. More than a few Voidglider elders have wicked scars and uncanny scrimshaw fetishes attesting to direct encounters with the krith.
Young and ambitious Vokun lordlings often seek to demonstrate their virility and prowess by mounting expeditions to hunt krith. Such harpoon hunts rarely end well, and resentful Voidglider scouts often return home masterless after these deadly expeditions.
The krith are the creation of Charles L. Harness, and come from his classic weird space opera, The Ring of Ritornel (1968).