Step 1: Understanding the Concept:
"Frontier Gandhi" is a nickname given because of a leader's Gandhian methods of non-violent protest, used in the North-West Frontier region (now in Pakistan), an area known for its warrior traditions, which made his choice of non-violence especially striking.
Step 2: Identifying the person.
Khan Abdul Ghaffar Khan earned this title. He founded the Khudai Khidmatgar movement, a non-violent resistance group against British rule in the Pashtun-majority North-West Frontier Province, and worked closely with Mahatma Gandhi and the Indian National Congress.
Final Answer:
Khan Abdul Ghaffar Khan is known as the Frontier Gandhi.