Indian writer and politician, outspoken in his advocacy of a militant anti-British nationalism in the Indian National Congress (Congress Party) and as a leader of the Hindu supremacy movement.

After studying law at the Government College in Lahore, Lajpat Rai practiced at Hissar and Lahore, where he helped to establish the nationalistic Dayananda Anglo-Vedic School and became a follower of Dayananda Sarasvati, the founder of the conservative Hindu society Arya Samaj (“Society of Aryans”). After joining the Congress Party and taking part in political agitation in the Punjab, Lajpat Rai was deported to Mandalay, Burma (Myanmar), without trial, in May 1907. In November, however, he was allowed to return when the viceroy, Lord Minto (Minto, Gilbert Elliot-Murray-Kynynmound, 1st earl of, Viscount Melgund Of Melgund), decided that there was insufficient evidence to hold him for subversion. Lajpat Rai's supporters attempted to secure his election to the presidency of the party session at Surat in December 1907, but elements favouring cooperation with the British refused to accept him, and the party split over the issues.

During World War I, Lajpat Rai lived in the United States, but he returned to India in 1919 and in the following year led the special session of the Congress Party that launched the Noncooperation Movement. Imprisoned from 1921 to 1923, he was elected to the legislative assembly on his release. In 1928 he introduced the legislative assembly resolution for the boycott of the British Simon Commission on constitutional reform. Shortly thereafter he died, after being attacked by police during a demonstration.

Lajpat Rai's most important writings include The Story of My Deportation (1908), Arya Samaj (1915), The United States of America: A Hindu's Impression (1916), and Unhappy India (1928).