Ratsasan (transl. Demon) is a 2018 Indian Tamil-language crime thriller film directed by Ram Kumar. The film stars Vishnu Vishal, Amala Paul, and Saravanan, while Ammu Abhirami, Kaali Venkat, Vinodhini Vaidyanathan, and Ramdoss play supporting roles. The film features music and a background score composed by Ghibran, cinematography by P. V. Shankar, and editing by San Lokesh. It tells the story of an aspiring film director who becomes a police officer after his father's death and tries to track down a serial killer.

The film was released on 5 October 2018 to critical acclaim. It was remade in Telugu as Rakshasudu and in Hindi as Cuttputlli.