Drider

Driders are drow that have been transformed from the waist down so they have the body of a spider. The transformation is typically a punishment for offending their goddess, or failing a test of Lolth.

Ecology
Once a promising drow reaches 6th level, a high-level priestesses in good standing with Lolth may test the drow's loyalty to the Queen of Spiders. If the promising drow fails the test, he or she will be transformed into a drider, (However this has changed from a punishment to a blessing according to the Dungeons & Dragons 4th edition). This transformation is extremely painful and lasts at least twelve hours. Driders develop a poisonous bite. Their digestion changes and they must drink the blood of living creatures for sustenance. Because they have failed Lolth's test, they become outcasts from their own people.

Driders still maintain the spells and special abilities they had developed as a drow, thus there can exist any character class of drider. They retain intelligence and memories. This makes them bitter, spiteful creatures. Some hunt for magic powerful enough to undo the transformation. Later in Sacrifice of the Widow some driders find out that they are the Chosen of Selvetarm and the Children of Lolth.

Typical physical characteristics
Driders are centaur-like creatures, appearing as drow from the waist up, with their lower portions replaced by the abdomen and legs of immense spiders.

In previous editions, driders appear genderless due to bloating, but able to magically reproduce. Currently in the 3.5 Edition D&D, driders seem to retain their gender and characteristics after the transformation, but cannot breed.

Society
Driders are the bogeyman of drow society—the ultimate warning to obey the will of Lolth. Dark elves and drider despise each other, but they often live in close proximity, with the drow using driders to weed out the weak.

The drow aberrations can be found working alone or in small groups. They are often accompanied by tiny, huge, and gigantic spiders.

Driders speak Common, Elvish, and Undercommon.

Trivia
The term "eight legs," a reference to a drider, was used among the drow as a threat.