The person referred to as `Frontier Gandhi` is Khan Abdul Gaffar Khan. Sheikh Abdullah, Manilal Gandhi, and Gopal Krishna Gokhale are not referred to by this nickname. Khan Abdul Gaffar Khan was a prominent political leader in the Indian independence movement. He was a close associate of Mahatma Gandhi and played a significant role in the non-violent resistance against British rule in India. Khan Abdul Gaffar Khan was from the North-West Frontier Province (now part of Pakistan), which is why he is known as `Frontier Gandhi`. He led the Khudai Khidmatgar movement, also known as the "Red Shirts", which advocated for non-violence and social reforms. Khan Abdul Gaffar Khan`s commitment to non-violence and his efforts for the independence of India earned him the nickname `Frontier Gandhi`.