Jim Jones convinced his 1000 followers they would all have to commit suicide since he was going to die.
Shoko Asahara convinced his followers to release a weapon of mass destruction, the deadly sarin gas, on a Tokyo subway.
The Order of the Solar Temple lured the rich and famous, including Princess Grace of Monaco, and convinced them to die a fiery death now on Earth to be reborn on a better planet called Sirius.
Charles Manson convinced his followers to kill, in an attempt to incite an apoca.