Siva Manasula Sakthi (lit. 'Sakthi in Siva's heart') also known by the initialism SMS, is a 2009 Indian Tamil-language romantic comedy film written and directed by debutant M. Rajesh, a former assistant of director S. A. Chandrasekhar. It stars Jiiva and newcomer Anuya Bhagwat, a student of Pune Film Institute, in the lead roles, with Santhanam, Urvashi and Sathyan appearing in supporting and Arya appearing in a cameo role.

The film released on 13 February 2009. Despite initially gaining mixed reviews, it became highly successful at the box office and has since achieved cult status. The film's soundtrack by Yuvan Shankar Raja was extremely popular and hailed as a blockbuster. The film was later remade in Telugu as Shiva Manasulo Shruti with Sudheer Babu and Regina Cassandra and released in 2012.