Wikimedia commons
Mahatma Gandhi.
He was assassinated in 1948.
Though in school he was rated as only "good at English, fair in Arithmetic and weak in Geography," he would go on to become a lawyer and spend twenty years in South Africa before returning to a still-colonial India.
There he led the Indian independence movement, which culminated to the Indian Independence Act of 1947.
His philosophy of satyagraha - or mass nonviolent protest - would become a tool of oppressed people around the world, inspiring the likes of Nelson Mandela and Dr. Martin Luther King, Jr.
For this we call him Mahatma, or great soul.