The Aum Supreme Truth cult is a well-publicized homicidal cult, some of its members having released bags of toxic chemicals into the center of the Tokyo subway on March 20, 1995, killing twelve people and injuring more than five thousand.
Charles Manson, inspired by a bizarre misinterpretation of the Beatles' song "Helter Skelter", led a group he called "the Family" to murder Sharon Tate, the wife of film director Roman Polanski.
Historically the cult of Thuggee murdered hundreds of thousands of people in 19th-century India.
Many religions have practised human sacrifice (for example, in Hawai'i as recently as the early 1800s), sometimes on an enormous scale (see for example the Aztecs), but the controversial distinctions between cult and religion and between sacrifice and terrorism become problematic in many cases.
explanation of how a cult can turn homicidal?
See also Cult suicides, Totalitarian religious group..