Nayakan ( transl. Hero) is a 1987 Indian Tamil-language epic crime drama film written and directed by Mani Ratnam. Produced by Muktha Srinivasan, the film stars Kamal Haasan, Saranya (in her feature debut) and Karthika, with Janagaraj, Vijayan, M. V. Vasudeva Rao, Delhi Ganesh, Nizhalgal Ravi, Nassar and Tara in supporting roles. It revolves around the gradual transformation of Velu Naicker (Haasan) from an ordinary slum dweller to a highly respected don.

Nayakan is loosely based on the life of the Bombay underworld don Varadarajan Mudaliar and the American film The Godfather (1972). Ratnam was initially approached to remake the Hindi film Pagla Kahin Ka (1970) for Srinivasan and Haasan, but refused. He instead suggested two other stories, one of which impressed Haasan and became Nayakan. Cinematography was handled by P. C. Sreeram, and editing by B. Lenin and V. T. Vijayan. Filming began in late 1986, taking place primarily in Madras and to a lesser extent, Bombay.

Nayakan was released on 21 October 1987, Diwali day. It became a critical and commercial success, running for over 175 days in theatres. Haasan's performance earned him the National Film Award for Best Actor. The film also earned the National Awards for Best Cinematography (Sreeram) and Best Art Direction (Thota Tharani). Nayakan was India's official submission for the Best Foreign Language Film at the 60th Academy Awards, but it was not nominated. It was included in Time's list of the "All-Time 100 Best Films" and News18's "100 greatest Indian films of all time". The film was remade in Hindi as Dayavan (1988).