Jawaharlal Nehru
India's first prime minister, who built its democracy and its planned economy and invented non-alignment as a foreign policy.

He was the son of a wealthy Allahabad barrister, educated at Harrow and Trinity College, Cambridge, called to the bar at the Inner Temple, and by his own account more comfortable in English than in any Indian language. He spent roughly nine years of his life in British prisons and wrote most of his books there. When India became independent at midnight on 15 August 1947, he gave the speech about a tryst with destiny and then governed for sixteen years, the formative period in which almost every durable feature of the Indian state was set.
The partnership with Gandhi
Nehru and Gandhi were an odd and productive pair. Gandhi was a religious man who idealized the village, distrusted industry, and could summon mass action Nehru could not. Nehru was a secular socialist who thought village India was a place of poverty and caste tyranny to be escaped through steel mills and dams. Gandhi named him his political heir anyway, on the reasoning that Nehru could speak to the modern world and would not compromise on Hindu-Muslim unity.
That second quality mattered enormously in 1947. Partition killed somewhere between several hundred thousand and two million people and displaced perhaps fifteen million. Pakistan had been created as a homeland for Muslims, and there was a plausible logic by which India would define itself as a Hindu state in response. Nehru refused, insistently and at some political cost, and India was written as a secular republic with roughly forty million Muslim citizens remaining.
What he built
Three things, mainly.
A working democracy in a poor country, which political science at the time considered close to impossible. India held universal-suffrage elections from 1951 with an electorate that was largely illiterate, and Nehru submitted to parliamentary questioning, tolerated a hostile press, and never showed any interest in becoming a strongman despite having no serious rival.
A planned economy. Five-year plans, state ownership of heavy industry, import substitution, and licensing of private investment. He called the dams and steel plants the temples of modern India. It delivered a scientific and industrial base and a growth rate so mediocre that economists coined the phrase Hindu rate of growth for it. The licensing system also created a permit bureaucracy that took until the 1991 reforms to begin dismantling.
Non-alignment. With Tito, Nasser, and Sukarno he built a bloc of newly independent states refusing to join either Cold War camp, formalized at Bandung in 1955 and as a movement in 1961. It gave poor countries leverage neither superpower would otherwise have granted them, and it was frequently criticized as high-mindedness that ended in taking Soviet arms anyway.
The failure
The last of these broke on China. Nehru promoted friendship with Beijing, sponsored its international rehabilitation, and popularized the slogan Hindi-Chini bhai-bhai, Indians and Chinese are brothers, while a border dispute over Aksai Chin and the eastern sector went unresolved. He then authorized a forward policy of planting small posts in contested territory without the military capacity to hold them. In October 1962 China attacked, routed the Indian army, advanced deep into Assam, and withdrew unilaterally. Nehru never recovered; he died in May 1964.
The inheritance
Modern India argues about him constantly, which is a measure of how much of it he set. The secular constitution, the state-heavy economy, the non-aligned instinct, and the political dynasty that ran the Congress party for three generations are all his. The current governing party defines itself substantially against the first of those, which is the clearest evidence of how thoroughly he shaped the terms.