Supernatural gangs.
Gangs are groups of violent and merciless criminals who commit crimes for benefit, such as robbery or smuggling drugs. They will even kill innocents for pleasure. Perry once noted that underground gangs were like supernatural terrorists.
While many gangs consist of humans, there are also many gangs that consist of supernaturals who live as rogues and outside the FRU's jurisdiction. Vampires, werewolves, and hybrids are most common to join gangs for survival.