Mayankote Kelath Narayanan (born 10 March 1934) is an Indian diplomat and former IPS officer. He was National Security Adviser of India from 2005 to 2010, assuming the role after the demise of his predecessor Jyotindra Nath Dixit in January 2005.Subsequently he served as Governor of West Bengal from 2010 to 2014.The Government of India awarded him the civilian honour of Padma Shri in 1992.

M K Narayanan hails from Kelath family at Ottapalam, Palakkad, a district of the state Kerala. Narayanan completed his graduation from Loyola College, Chennai. He is married to Padmini Narayanan and the couple has a son, Vijay, and a daughter, Meena. Their son-in-law Ajit Nambiar is Chairman and Managing Director of BPL Ltd.

M. K. Narayanan joined the Indian Police Service in 1955 and passed out as the best all-round officer of his batch. After a brief stint as Sub-Divisional Police Officer in the erstwhile State of Madras, he went on deputation to the Intelligence Bureau in February 1959. The rest of his service career was spent under the Government of India, mainly in the Intelligence Bureau, in which he dealt with a whole range of issues concerning internal and national security.

He headed the Intelligence Bureau (IB) from 1987 to 1990, before heading the Joint Intelligence Committee. He became Chief of the IB again in 1991, before retiring in 1992. He was the Special Adviser for Internal Security to the Prime Minister of India beginning in May 2004. He was Indian National Security Adviser with the rank of Minister of State from 2005 to 2010. He played a significant role in the negotiation of the landmark Indo-US Civil Nuclear Agreement of 2008.

On 24 January 2010 Narayanan was appointed as Governor of West Bengal as a retirement posting due to his closeness to the UPA Administration. He took over from Gopalkrishna Gandhi, who had a few disagreements with the CPM-ruled West Bengal on critical issues like violence in Nandigram and Singur.