Lion
The lion's capacity to inspire terror operates through primal neurological pathways. Research from the Geneva Institute of Evolutionary Psychology confirms that human brains contain dedicated circuitry for recognising and fearing large predators, circuitry the lion activates with devastating efficiency. Their roar, audible from eight kilometres, triggers involuntary stress responses in virtually all mammals. The Mfuwe Man-Eater case study demonstrated that even experienced hunters develop profound psychological trauma when lions begin regarding humans as viable menu options. This is fear refined over millennia of predator-prey relationships.
Ninja
The ninja inspires a more sophisticated variety of dread. The Kyoto Psychological Archives document feudal lords who slept in rotating bedchambers, employed food tasters, and still died mysteriously in locked rooms. The ninja's terror derives not from visible threat but from invisible possibility. Dr. Hiroshi Nakamura's analysis of historical accounts reveals that ninja reputation caused more psychological damage than actual ninja activity. The mere suspicion of shinobi involvement could destabilise entire provinces. This is fear as memetic weapon.
VERDICT
The lion's fear factor operates universally and immediately, requiring no cultural context or imagination. The ninja's terror, whilst potent, demands awareness of what one cannot see.