Lolth was the spider-bodied goddess of darkness, treachary and the Underdark, as well as being the patron goddess of the Drow. From the fact that the theocracy set up in her name was matriachal, it's reasoanble to assume that she was also somewhat misandristic (for comparisson, no other society in TDDC, including the republic later formed by the Drow, has been shown or mentioned to discriminate on gender in any way).
Historians dispute as to whether she became the patron of the Drow after they arrived in the Underdark, fleeing the Vampire Kings, or whether they fled to the Underdark because Lolth was their patron, but the end result was that the Drow resided in the Underdark under Lolth's patronage. When Blibaal gave a portion of her power to the Kua Toa, Lolth gave an even greater portion of her power to the Drow, allowing them to grow into the mighty Spider Empire.
Lolth was eventually ambushed and killed by her rival, Delvash, after he learned the secret of The Death Equation from Tiamat. The resulting loss of power among her priestesses eventually led to the collapse of the Spider Empire and the formation of the Drow Republic.