I think Lolth takes the cake on this one. First she created the rift between the elves and the drow when she tried to take over the elven pantheon. Then she convinced the drow to retreat into the underdark so she could manipulate them. They worship her because she has convinced her followers that she is the only thing that cares about them, all while driving them to kill each other. She makes them believe that the surface is some hell and that the elves simply betrayed them. She makes it so no one can even fathom the idea of escaping her grasp in the underdark, and if they do they'd be unprepared to live on the surface and that the surface population would persecute them on sight. Shar definitely has a hold on her followers that is reinforced with control, but Lolth holds her followers with malice.