Admiral Adhar Kumar Chatterji (4 March 1914 – 6 August 2001) was an Admiral in the Indian Navy. He served as the 5th Chief of the Naval Staff, from 4 March 1966, until 28 February 1970. He was the first Indian officer of the navy to hold the rank of full Admiral. He is credited with the transformation of the Indian Navy. He made sweeping changes and restructured the navy, creating the Western and Eastern Naval Commands and the Western Fleet. Under him, the Indian Navy also entered the submarine age, with the commissioning of INS Kalvari (S23) in 1967.