Udham Singh (26 December 1899 – 31 July 1940), was a revolutionary belonging to the Ghadar Party best known for his assassination in London of Michael O' Dwyer, the former lieutenant governor of the Punjab in India, on 13 March 1940.
The assassination was in revenge for the Jallianwala Bagh massacre in Amritsar in 1919.
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 of Punjab and his anti-colonial sentiment.Udham Singh is a well-known figure of the Indian independence movement.
He is sometimes referred to as Shaheed-i-Azam Sardar Udham Singh (the expression "Shaheed-i-Azam", means "the great martyr").
A district (Udham Singh Nagar) of Uttarakhand was named after him to pay homage in October 1995 by the then Mayawati government.