Sir Benegal Narsing Rau CIE (26 February 1887 – 30 November 1953) was an Indian civil servant, jurist, diplomat and statesman known for his role as the constitutional advisor to Constituent Assembly. He was also India's representative to the United Nations Security Council from 1950 to 1952.
Rau helped draft the constitutions of Burma in 1947 and India in 1950. He was the constitutional advisor of the constituent assembly of India. He was India's representative to the United Nations Security Council from 1950 to 1952, and was serving as its president when it recommended armed assistance to South Korea in June 1950. Later he was a member of the Korean War post Armistice United Nations Command Military Armistice Commission (UNCMAC).
A graduate of the Universities of Madras and Cambridge, Rau entered the Indian civil service in 1910. After revising the entire Indian statutory code (1935–37), he was knighted in 1938 and was made judge of the Bengal High Court at Calcutta in 1939. His writings on Indian law include a noted study on constitutional precedents as well as articles on human rights in India. He served briefly (1944–45) as Minister of Jammu and Kashmir state. From February 1952 until his death, he was a judge of the International Court of Justice at The Hague. Before his election to the court, he was regarded as a candidate for secretary-general of the United Nations. Sir B. N. Rau's brothers were Governor of the Reserve Bank of India Benegal Rama Rau and journalist and politician B. Shiva Rao.