Step 1: Historical background.
The Champaran Satyagraha of 1917 was the first Satyagraha movement organized by Mahatma Gandhi in India. It was launched in Bihar against the exploitation of indigo cultivators by British planters.
Step 2: Gandhi's leadership.
Gandhi was invited by local leaders like Rajkumar Shukla to Champaran. He took up the cause of farmers and led a peaceful movement demanding relief from oppressive practices.
Step 3: Conclusion.
Thus, Mahatma Gandhi led the Champaran Satyagraha.
Final Answer: \[ \boxed{\text{Mahatma Gandhi}} \]