Lolth is the goddess and indirect ruler of the drow race. She rules a massive empire from the Demonweb, the 66th "layer" of the Abyss.
In her preferred form, Lolth is a stunningly beautiful, ageless drow woman, with black skin, white hair, red eyes, and pointed ears. She wears rich but revealing spider-themed clothing, which also prominently feature the color red, and she wields a poisoned scourge (a barbed, multi-tailed metal whip). Her true form is that of a bloated black widow spider the size of an elephant, which she transforms into when her drow guise is killed. This usually causes quite a shock to her opponents, who are forced to kill her twice.
As a deity, Lolth discorporates when sufficiently wounded. Her body is destroyed, but she lives on in a non-physical state anywhere from a few months to three years. After this period, she reforms. Lolth only discorporates in her true form: she can be "killed" in her drow form, but reverts to her spider form immediately afterwards, very much alive. She also has superhuman physical and mental faculties, has various poisons at her disposal, and can fill areas with searing black flames called darkfire.
Lolth is revered by the drow and is also served by the small, spiderlike humanoids called chitines. Strangely, the two species hate each other, and that's just how Lolth likes it. She occasionally creates aspects, creatures that mimic her spider form's appearance and capabilities, and that can shapeshift into drow form. Her other minions include yochlols, bebiliths, other demons, and monstrous spiders.