Anniyan ( transl. Stranger) is a 2005 Indian Tamil-language psychological action thriller film directed by S. Shankar and produced by V. Ravichandran. The film stars Vikram as a law-abiding lawyer who suffers from dissociative identity disorder, and develops two other identities: a fashion model, and a murderous vigilante seeking to eradicate corrupution. The cast also includes Sadha, Vivek, Nedumudi Venu, Nassar and Prakash Raj.

Shankar conceived the film in mid-2003 during the post-production period of his previous film Boys. He based the film on his own life experiences during his formative years when he was disturbed by what he saw around him and his eventual displeasure with the society. Pre-production for Anniyan began in November 2003 and principal photography in March 2004. The making of the film, which included numerous production delays, took 14 months. The film was shot at Hyderabad, Thanjavur, Tindivanam and Chennai. The song sequences were filmed in Mumbai, Malaysia, Amsterdam and Tenkasi. The film was notable for its recreation of the Tyagaraja Aradhana music festival and the extensive use of time slice photography in an action sequence.

Cinematographer V. Manikandan discontinued the project halfway through, until he was replaced with Ravi Varman. The technical departments were headed by V. T. Vijayan (editing), Sabu Cyril (production design), and Peter Hein (action choreography). The soundtrack was composed by Harris Jayaraj, who was in his first collaboration with the director. The film was touted as the director's magnum opus and was budgeted at ₹263.8 million, making it at the time of its release the most expensive Indian film ever made. Notably, it was the first South Indian film to obtain institutional finance, and it had the highest insurance coverage available for films at that time.

Anniyan was released on 10 June 2005 and became a commercial success, and in addition to winning a record breaking eight Filmfare Awards and six State Film Awards, it also won a National Award in the Special Effects category.