Lone wolf terrorism, or lone actor terrorism, is a type of terrorism committed by an individual who both plans and commits the act on their own. The precise definition of the term varies, and some definitions include those directed by larger organizations and small cells. Other names for the phenomenon include lone operator terrorism, freelance terrorism, solo terrorists, and individual terror cells. It is similar to but distinct from the concept of leaderless resistance.
The name 'lone wolf' is derived from the notion of a lone wolf, a pack animal that has left or been excluded from its pack. The term was popularized in the late 1990s by white supremacist activists Tom Metzger and Alex Curtis, and further from the FBI and the San Diego Police Department's investigation into Curtis, named Operation Lone Wolf. Compared to the general population and members of organized terrorist groups, lone wolf terrorists are more likely to have been diagnosed with a mental illness, though it is not an accurate profiler.
Stochastic terrorism refers to political or media figures publicly demonizing a person or group, inspiring their supporters to commit a violent act against the target of the speech. Unlike incitement to terrorism, this is done using indirect, vague or coded language, which allows the instigator to plausibly disclaim responsibility for the resulting violence. Global trends point to increasing violent rhetoric and political violence, including more evidence of stochastic terrorism. It is in this manner that the stochastic terrorist is thought to randomly incite individuals predisposed to acts of violence. Because stochastic terrorists do not target and incite individual perpetrators of terror with their message, the perpetrator may be labeled a lone wolf by law enforcement, while the inciters avoid legal culpability and public scrutiny. In their 2017 book The Age of Lone Wolf Terrorism, criminologist Mark S. Hamm and sociologist Ramón Spaaij discuss stochastic terrorism as a form of "indirect enabling" of terrorists. They write that "stochastic terrorism is the method of international recruitment used by ISIS", and they refer to Anwar al-Awlaki and Alex Jones as stochastic terrorists.