Thalai Nagaram (transl. Capital city) is a 2006 Indian Tamil-language gangster action film written and directed by Suraj and produced by V. Ravichandran. The film stars Sundar C in his lead acting debut and Jyothirmayi, while Vadivelu, Prakash Raj, Judo. K. K. Rathnam, K. S. Ravikumar, and Bose Venkat play supporting roles. The soundtrack was composed by D. Imman, cinematography was handled by K. S. Selvaraj and editing by Mu. Kasi Viswanath.

The film is a remake of the 1991 Malayalam film Abhimanyu, The film tells the story of a man who sacrifices his life to kick out gangsters who ruin other's lives.

The film was followed by Naai Sekar Returns (2022), a comedy spin-off of Vadivelu's character in the film, and a standalone sequel Thalainagaram 2 (2023).