A cult can be religious or secular. It is simply a small, unestablished, non-mainstream group that typically revolves around a single, charismatic leader. People like David Koresh of the Branch Davidians, who was born in Houston.
Another example of such a leader would be Marshall Applewhite who led Heaven's Gate and convinced 39 members to participate in a mass suicide in order to reach what they believed was an extraterrestrial spacecraft following the Hale–Bopp Comet.
Charles Manson, whose "family" committed nine murders at his request, is also an example of a cult leader.
Author/attorney Carla Powers, who survived living as part of a cult when she was a young girl, and Texas Southern University distinguished professor of history Cary Wintz discuss the appeal and volatility of cult leaders with Isiah Carey.