Thadam (transl. Trail) is a 2019 Indian Tamil-language crime thriller film written and directed by Magizh Thirumeni. Produced by Inder Kumar, the film stars Arun Vijay in a dual role along with Vidya Pradeep, Tanya Hope, and Smruthi Venkat. The music was composed by Arun Raj, with cinematography by Gopinath and editing by N. B. Srikanth. In the film, police officers try to solve a murder case involving lookalike suspects arrested on the basis of a pictorial evidence.

Thadam was released theatrically on 1 March 2019, opening to critical acclaim with praise for Arun Vijay's performance and the writing. It was commercially successful, becoming one of the highest-grossing films of the year in Tamil Nadu. The film was remade in Telugu as Red (2021), and in Hindi as Gumraah (2023).