Velikkakathu Sankaran Achuthanandan (Malayalam : വേലിക്കകത്ത് ശങ്കരന് അച്യുതാനന്ദന്) (born 20 October 1923) is an Indian politician who was Chief Minister of Kerala from 2006 to 2011. He has been Leader of the Opposition in Kerala since 2011. Achuthanandan was a member of the Politburo of the Communist Party of India (Marxist) beginning in 1985, and until July 2009, when he was reverted to the Central Committee of the party owing to his ideological dispositions. He is a mass leader respected for integrity.
Achuthanandan was one of the founding leaders of the CPI (M) in India, and has played a major role in building the party cadre in the state of Kerala.
Achuthanandan initiated various actions as the Chief Minister including: the demolition drive in Munnar which claimed back acres of illegally occupied land, the demolition drive in Kochi M. G. Road which claimed back the long lost shoulder of the road, anti-piracy drive against film-piracy, his struggle against the Lottery mafia in the state. He was instrumental in convicting former minister R. Balakrishna Pillai on charges of corruption. Achuthanandan also took the lead in promoting Free Software in the state, and especially in adopting free software in the public education system of the state.