Siruthai (transl. Cheetah) is a 2011 Indian Tamil-language action comedy film directed by Siva, who is also one of its co-writers. It is a remake of the 2006 Telugu film Vikramarkudu, directed by S. S. Rajamouli. It stars Karthi playing dual roles, alongside Tamannaah Bhatia and comedian Santhanam. The film was produced by K. E. Gnanavelraja and features music by Vidyasagar. The story revolves around "Rocket" Raja, a petty thief who comes across a little girl says that he's her father. When he learns the truth about his lookalike Rathnavel Pandian, who's an honest cop, he decides to turn a new leaf and help get rid of a crime gang.

It was released during Pongal on 14 January 2011. Generally the film got positive responses, and was a success at the box office. The film was remade in Bengali-language in 2012 as Bikram Singha: The Lion Is Back. In 2024, the film made its official debut on Blu-ray in the United Kingdom. The success of the film led to the director Siva being known as "Siruthai Siva" from then on.