Benjamin Cyrus

Benjamin Cyrus was a cult leader in the season 4 episode Minimal Loss.

Background
Cyrus is the leader of a cult known as the Sepretarian Sect, a quasi-religious commune of Libertarians located in La Plata County, Colorado. The cult itself started out as a self-sustaining commune led by Leo Kane, who is now serving 17 years in prison for assaulting four IRS agents. Cyrus then took over the commune, proclaiming himself a Messiah of sorts. He was identified by local authorities as the perpetrator of child sexual abuse among his cult members. It is revealed that he, himself, is married to a young adolescent girl. In the past, he had been convicted of three counts of statutory rape. In prison, he volunteered at the prison hospital.

Minimal Loss
Spencer Reid and Emily Prentiss are called in to meet with him, and are introduced as "child interview experts". He holds them hostage after the death of a local social worker at the hands of Colorado State Police. Cyrus then accuses Prentiss of knowing about the raid, and orders her beaten, all the while asking if she knows of the existence of an FBI agent in the complex. Prentiss refuses to reveal that she and Reid are FBI and takes the beating stoically.

Rossi offers to speak to Cyrus, and asks him to let the children in the compound go. Cyrus refuses, saying he will not release them from his "protection". Cyrus then later prepares a mass suicide ritual to root out the unbelievers. The ritual is a bluff, however, and those who did not drink the wine were released.

Leo Kane (Jeff Fahey) is later interviewed by Derek Morgan, who tells Morgan of Cyrus' past. Cyrus' mother had been five months pregnant when she arrived at the Liberty Ranch and, as Charles grew up among Kane's followers, he noticed the young man was special. He had an astounding memory for anything that he read, but he was also very mouthy. When he was 17, some young girls told Kane that Charles had been "messing with them," and Kane had kicked him out. Some years later, he returned and told Kane his mother had died and he "found God." When Morgan asked Kane how a young man managed to oust him from his own ranch, Kane replies, "One day he came to me and said that God told him that I should leave the ranch. When I said that if God felt that way he could tell me Himself he put a gun to my head and said, 'He just did.'" Embittered, Kane tells Morgan it had taken him 20 years to build that ranch and he'll do whatever he can to send Cyrus "straight to hell."

After negotiations, Cyrus agrees to let the children go and surrender. He has, however, rigged the compound with explosives, which kill another State Agent. Cyrus' body is found dead on the floor.