A soldier developed by the CIA, dubbed the "Perfect Soldier". His codename, Null, befits his status as a non-entity without feelings, memories, or even a serial number.

After each mission, Null is sealed in a fluid-filled culture tank, where he undergoes a complete sensory deprivation to reset his memory.

This sharpens Null's senses so that he experiences each mission as a newborn babe enters the world. It allows him to recognize and learn his enemy's techniques faster than any normal human could.

Once sent into battle, Null uses his machete to dispatch his opponents with the inhuman agility of a carnivorous beast.

Null eventually becomes the soldier known as Gray Fox.

In 1966, Mozambique was embroiled in a struggle for independence. Among the rebel guerrillas was a child soldier who killed dozens of government soldiers with just a knife. His enemies were caught off guard by the youngster's innocent, frank demeanor, only to be slaughtered by the ruthless hunter lurking within him. Since he spoke a few words of German, the boy was known and feared as "Frank Jaeger", the Frank Hunter.

But he was captured by the Philosophers and subjected to human experimentation. He lost everything, and became Null. The one who finally freed him was Naked Snake.