Udham Singh (born Sher Singh; 26 December 1899 – 31 July 1940) was an Indian revolutionary belonging to Ghadar Party and HSRA, best known for assassinating Michael O\'Dwyer, the former lieutenant governor of the Punjab in India, on 13 March 1940. The assassination was done in revenge for the Jallianwala Bagh massacre in Amritsar in 1919, for which O\'Dwyer was responsible and of which Singh himself was a survivor.Singh was subsequently tried and convicted of murder and hanged in July 1940. While in custody, he used the name \'Ram Mohammad Singh Azad\', which represents the three major religions in India and his anti-colonial sentiment. Singh was a well-known figure of the Indian independence movement. He is also referred to as Shaheed-i-Azam Sardar Udham Singh (the expression "Shaheed-i-Azam" means "the great martyr"). A district (Udham Singh Nagar) was named after him as a homage by the Mayawati government in October 1995.