Kaithi (transl. Prisoner) is a 2019 Indian Tamil-language action thriller film directed by Lokesh Kanagaraj. It is produced by S. R. Prakash Babu and S. R. Prabhu under Dream Warrior Pictures and co-produced by Tiruppur Vivek under Vivekananda Pictures. It stars Karthi in the lead role, along with Narain, Arjun Das, Harish Uthaman, George Maryan, and Dheena in pivotal roles. In the film, a recently released prisoner races against time to drive poisoned cops to a hospital in exchange for meeting his daughter while evading criminals chasing him.

Lokesh initially worked on two scripts after the success of Maanagaram (2017), which he scrapped working on due to issues regarding the extensive research and casting process, until he came up with a news article about an ex-prisoner's life. He initially wanted Mansoor Ali Khan to play the lead role, but during the writing process, Karthi was demanded to play the lead, with the scale of the budget being increased further. Principal photography began in December 2018, and was completed by August 2019. The film was entirely shot at night, without any daytime sequences taking place during the shoot. It is a songless film, with the background score being composed by Sam C. S. The cinematography and editing were handled by Sathyan Sooryan and Philomin Raj, respectively.

Kaithi was released on October 25, 2019, ahead of the Diwali festival. It opened to positive reviews from critics. Following the positive reception, the film became a box-office success, grossing ₹105 crore. The film was further selected for official screening at the International Indian Film Festival Toronto (IIFFT) in August 2020 and had won two Ananda Vikatan, three Norway Tamil Film Festival, SIIMA, and four Zee Cine Awards, respectively. The story is the first installment of the Lokesh Cinematic Universe (LCU), which follows the dismantling of drug trafficking. Kaithi is followed up in Vikram (2022) with Narain reprising his role as Bejoy, while George Maryan reprises his role as Napoleon in Leo (2023), also directed by Lokesh. A sequel, titled Kaithi 2, is in development.