S. Sadhasivam is an Indian politician who is a Member of Legislative Assembly of Tamil Nadu. He was elected from Mettur as a Pattali Makkal Katchi candidate in 2021. In 2025, Sadhasivam declared support for PMK President Anbumani Ramadoss, which resulted in him being censured by party founder S. Ramadoss, and, along with 2 other PMK MLAs, later joined the faction of the PMK led by Anbumani.