Mahanadhi (transl. The Great River) is a 1994 Indian Tamil-language crime drama film directed by Santhana Bharathi and co-written by Kamal Haasan. The film stars Haasan and Sukanya, with S. N. Lakshmi, Tulasi, Shobana, Dinesh, Poornam Viswanathan, Rajesh and V. M. C. Haneefa in supporting roles. It revolves around a widower and his family going through many miseries due to the machinations of a con artist.

The idea for Mahanadhi originated when Haasan discovered his domestic help's plan to kidnap his daughters for a ransom. After he completed the story, novelist Ra. Ki. Rangarajan made inputs, and was subsequently credited as the dialogue writer. Cinematography was handled by newcomer M. S. Prabhu, and editing was handled by N. P. Sathish. It was the first film in India to make use of Avid Technology. The film deals with several issues such as corruption and child trafficking.

Mahanadhi was released in theatres on 14 January 1994, Pongal day, and was both critically and commercially successful. The film won two National Film Awards: Best Feature Film in Tamil and Best Audiography, and two Tamil Nadu State Film Awards: Special Prize (Best Film) and Best Stunt Coordinator (Vikram Dharma).