Udham Singh (26 December 1899 – 31 July 1940) was an Indian revolutionary best known for assassinating Michael O'Dwyer on 13 March 1940 in what has been described as an avenging of the Jallianwalla Bagh Massacre. Singh is a prominent figure of the Indian independence struggle. He is sometimes referred to as Shaheed-i-Azam Sardar Udham Singh (the expression "Shaheed-i-Azam," Urdu: means "the great martyr"). A district (Udham Singh Nagar) of Uttarakhand is named after him.
Singh was born Sher Singh on 26 December 1899, at Sunam in the Sangrur district of Punjab, India, to a Kamboj clan. His father, Sardar Tehal Singh Jammu (known as Chuhar Singh before taking the Amrit), was a railway crossing watchman in the village of Upalli. His mother died in 1901, and his father in 1907.
After his father's death, Singh and his elder brother, Mukta Singh, were taken in by the Central Khalsa Orphanage Putlighar in Amritsar. At the orphanage, Singh was administered the Sikh
initiatory rites and received the name of Udham Singh. He passed his
matriculation examination in 1918 and left the orphanage in 1919.