Kaithi (transl. Prisoner) is a 2019 Indian Tamil-language action thriller film directed by Lokesh Kanagaraj, who co-wrote it with Pon Parthiban, and 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, alongside Narain, Arjun Das, Harish Uthaman, George Maryan and Dheena. It is the first instalment in Lokesh Cinematic Universe. In the film, Dilli, a recently released prisoner races-against-time to drive poisoned cops to a hospital while evading criminals in exchange for meeting his daughter Amudha.

Lokesh Kanagaraj initially worked on two scripts after the success of Maanagaram, which he scrapped working on due to issues regarding the extensive research and casting process, until he came across 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 asked 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 a score 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, and received positive reviews from critics. Following the positive reception, the film became a box-office success grossing ₹105 crore worldwide, making it one of the top-grossing Tamil films of 2019. The film was further selected for official screening at the International Indian Film Festival Toronto (IIFFT) in August 2020 and won two Ananda Vikatan Cinema Awards, three Norway Tamil Film Festival Awards, South Indian International Movie Awards, and four Zee Cine Awards respectively. Kaithi is the first installment of the Lokesh Cinematic Universe, which is followed up in Vikram, with Narain reprising his role as Bejoy while George Maryan reprises his role as Napoleon in Leo. A sequel titled Kaithi 2 is in development.