Shaheed Udham Singh (Punjabi: ਉਧਮ ਸਿੰਘ Hindi:उधम सिंह् udham singh;) (December 26, 1899 – July 31, 1940) was born as Sher Singh; he belonged to Jammu clan of Kamboj lineage. He was a Sikh, a Punjabi Marxist and a nationalist mostly known for assassinating Sir Michael O'Dwyer in March 1940 in what has been described as an avengement of the Jallianwalla Bagh Massacre. Singh, one of the best-known of the more extremist revolutionaries of the Indian freedom struggle, is also sometimes referred to as Shaheed-i-Azam Sardar Udham Singh (the expression "Shaheed-i-Azam" means "king of martyrs").