Udham Singh (December 26, 1899 – July 31, 1940), born Sher Singh was an Indian independence activist, he was known for assassinating Michael O'Dwyer in March 1940 in what was an avengement of the Jallianwalla Bagh Massacre. Singh is considered one of the best-known of the more extremist revolutionaries of the Indian freedom struggle. He is sometimes referred to as Shaheed-i-Azam Sardar Udham Singh (the expression "Shaheed-i-Azam," means "the great martyr"). In 1940, almost 21 years after the Amritsar Massacre of 1919 in Punjab province of India, Singh shot dead Michael O'Dwyer at Caxton Hall in London. O'Dwyer was the Governor of the Punjab in 1919, when General Reginald Edward Harry Dyer ordered British troops to fire on unarmed Indian protesters, mostly Sikhs. The General Dyer had already died so Udham decided to kill O'Dwyer who had supported General Dyers' action. Sher Singh was born in Sunam (now Sunam Udham Singh Wala) in the Sangrur district of Punjab, as his parents died whilst he was young he was taken in by the Central Khalsa Orphanage Putlighar in Amritsar on October 24, 1907. He was administered the Sikh initiatory rites at the orphanage and received the new name Udham Singh.
After witnessing the Amritsar massacre Udham bathed in the holy sarovar (pool of nectar) and took a silent vow and solemn pledge in front of the Golden Temple to wreak a vengeance on the perpetrators of the crime and to restore honour to what he saw as a humiliated nation. After shooting O'Dwyer Udham was called "fighter for freedom" by The Times, London, and his action was said to be "an expression of the pent-up fury of the down-trodden Indian People". To this day he remains a heroic figure and his action is viewed as patriotic by Indians. On 31 July 1940, Udham Singh was hanged at Pentonville Prison, London. In July 1974, Udham Singh's remains were exhumed and repatriated to India at the request of S. Sadhu Singh Thind. He asked Indira Gandhi to force the then British Government to hand over Udham Singh's remains to India. Sadhu Singh Thind himself went to England as a special envoy of Indian Government and brought back the remains of the Shaheed. He was given a martyr's reception. He was later cremated in his birthplace of Sunam in Punjab and his ashes were immersed in the Ganga river. His life has been the subject of three films to date, with Shaheed Udham Singh (2000) being the most recent.