Kristen Gilbert, known as the "Angel of Death," was a serial killer who was a member of several dark groups, including the ISG (Invisible Serial Group). She is described as living a hermit lifestyle in secret bases after escaping from prison. Despite being retired, her deadly legacy continues to thrive, as do the legacies of many other serial killers. During her active period, Gilbert had a sympathetic and smiling demeanor, which helped her deceive those around her and avoid suspicion. She showed no apparent remorse for her actions, instead exhibiting sadism, charisma, joy and manipulation.