The Lurker is a vast sentient entity that resides within the Lifeswallower swamp, although it is capable of moving throughout all of the Sarangrave Flats, utilizing the many noxious rivers and streams that flow through that pestilential and depressing region. It is very much an aquatic creature of marsh and bog, preferring stagnant and foul water, rather than anything fresh. The Lurker appears within all three Chronicles of Thomas Covenant, with an especially significant role to play in The Third Chronicles
The Lurker is huge. Maybe not as big as The Worm of the World’s End, but still pretty damn big. It has never been viewed in its entirety, but is known to sport numerous massive tentacles, each as large as a tree trunk. On this basis, it may be safely assumed that the Lurker's bodily form is that of a many-armed squid with an expression that ranges from really angry to surprisingly scared.
Despite its vast bulk, the Lurker is an expert in camouflage within its preferred marshy terrain. Its presence is often only perceivable via a weird silver light flickering beneath the surface of the swamps and by those it's hunting becoming incapacitated by an eerie miasma, making it nigh on impossible for them to function or even breathe. Only the haruchai seem immune to this frightening effect.
For all its behemoth-esque size, the Lurker is an intelligent being. In The Third Chronicles of Thomas Covenant it is revealed that the Lurker has a name - Horrim Carabal (lit. "butt-hole monster"
from the old Estonian) - and by that stage, it proves itself to be capable of communication via its fear-filled worshippers, a really wimpy race known as the Feroce that act as interpreting intermediaries for their "high god", when it needs to converse with people. (Not that the Lurker traditionally feels this need much - it would much rather snatch up any human foolish enough to stray within the reach of its many tentacles and then either crush the life out of the unfortunate victim or drag him down to drown below the foetid surface of the swamp's waters. Not a nice way to go in either case). Before having acquired itself the Feroce as a pathetically damp congregation, the Lurker had utilized other creatures, namely lambent green floating bubbles of acid known as the skest to herd prey towards itself, but by the time of the Third Chronicles, this is no longer the case. It is unknown why the Lurker fell out with the skest - perhaps it got sick of the mess the latter kept dribbling onto its carpets.
The Lurker isn't exactly evil per se, but more likely amoral. It very much believes in looking after its own interests above all else. This has meant that, over the course of the Chronicles, it has switched its allegiance at least once, allying itself with whoever is most liable to do it some good. With that sort of propensity, perhaps the Lurker should have gone into politics?
The origins of the Lurker are shrouded in mystery within the dim and distant past. The majority of opinion is in favour of it having sprung from the eldritch filth and arcane pollution that continually emerged from the bowels of Mount Thunder to flow down Defile's Course and thence into the Sarangrave Flats. This is not as unlikely as it sounds - not only have numerous puissant banes been located under Gravin Threndor (the Illearth Stone and She Who Must Not Be Named being two very obvious ones), but Lord Foul has made the centre of the mountain his home before now, so who knows what evil and sorcerous outpourings headed eastwards from his personal plumbing? Plus of course, the Demondim constructed the breeding vats for the Ur-viles under Mount Thunder and the place has also been home to hundreds of thousands of cavewights for millennia, and those guys really aren't noted for their personal hygiene. Little wonder then that such a miasmic conflux of effluvia led to the quickening of perverse life within the Lifeswallower swamp, thus giving rise to the Lurker. It must be a truly revolting sight - imagine if you can your local sewage treatment works suddenly oozing into tentacular life. Real estate values around Treacher's Gorge consequently remain at an all-time low.
An alternative theory states that the Lurker actually had at least one parent and not just because, given an entirely free choice, no sentient being would be stupid enough to give itself a name as dumb-assed as Horrim Carabal. There are hints within the Third Chronicles that a previously unknown being even more hideous than the Lurker resides deep within an acid-filled lake in the abysses underneath Mount Thunder and that the Lurker itself views this unnamed entity as its own god. However, this supposition tends to be dismissed, since the providers of this information are the Feroce, who as has already been said really are pathetically puny, wimpish and generally not worth listening to.
For many eons, the Lurker allied itself with Lord Foul. For example, in the early ages of the Land, the Lurker gleefully accepted the role of executioner of Kelenbhrabanal, the original Ranyhyn herd leader, who was done to death after losing a poker match with the Despiser. (This is why the otherwise fearless Ranyhyn are terrified both of it and of the Sarangrave Flats). Furthermore, throughout the First and Second Chronicles, the Lurker has attempted on several occasions to do everything it can to put paid to Covenant, Linden and their various chums.
However, by the time of the Third Chronicles, the Lurker works out that Lord Foul's plan to use The Worm of the World’s End to destroy the Arch of Time and the entire cosmos along with it really isn't going to do it any favours, basically because it will die along with every other living thing. Okay, so initially it tries with the aid of the Feroce to kill Linden and take her Staff of Law, but this cannot be considered an evil act, since any right-thinking being would also do anything within its power to shut the whiny loser up once and for all. However, after this failed attempt at a mercy killing, the Lurker enters into an alliance with Covenant, variously helping him to traverse the vast Lifeswallower swamp at an incredible rate by tossing him from tentacle to tentacle in a bizarre mix of reverse Tarzan and keepy-uppy, then allowing the remnants of the Ur-viles and the waynhim to clamber amongst its tentacles to form some kind of huge Worm-averting dreamcatcher and finally lending a hand - or rather, a tentacle or two - to the forces of good in the big set-piece battle with the sandgorgons and the Skurj. Not all bad, then.
In our times, the Lurker has spawned enormous numbers of offspring, now those young Lurkers (not older than a hundred of years for sure) inhabit what remains of Kevin's Watch and its surroundings.