Sukhdev Thapar (Punjabi: ਸੁਖਦੇਵ ਥਾਪਰ, سُکھدیو تھاپر; Hindi: सुखदेव थापर) was an Indian freedom fighter who lived from 15 May 1907 to March 23, 1931). He is best known as an accomplice of Bhagat Singh and Shivaram Rajguru in the killing of a British police officer J.P. Saunders in 1928 in order to take revenge for the death of veteran leader Lala Lajpat Rai due to excessive police beating.
Sukhdev was an active member of the Hindustan Socialist Republican Association, being one of its most senior leaders. He is known to have started study circles at National College, (Lahore) in order to delve into India's past as well as to scrutinize the finer aspects of world revolutionary literature and the Russian Revolution. Along with Bhagat Singh, Comrade Ram Chandra and Bhagwati Charan Vohra, he started Naujawan Bharat Sabha at Lahore. The main aims of this organisation were to activate youth for freedom struggle, inculcate a rational scientific attitude, fight communalism and end the practice of untouchability.
Sukhdev also participated in the 1929 Prison hunger strike to protest against the inhuman treatment of inmates.
His letter to Mahatma Gandhi written just prior to his hanging, protesting against the latter's disapproval of revolutionary tactics, throws light on the disparities between the two major schools of thought among Indian freedom fighers.