Enthiran (transl. Robot) is a 2010 Indian Tamil-language science fiction action film co-written and directed by Shankar. It is the first instalment in the Enthiran film series. The film stars Rajinikanth in dual lead roles as a scientist and the robot he created. Aishwarya Rai Bachchan, Danny Denzongpa, Santhanam and Karunas play supporting roles. The soundtrack album and background score were composed by A. R. Rahman while the dialogues, cinematography, editing and art direction were handled by Madhan Karky, R. Rathnavelu, Anthony and Sabu Cyril and action sequences was done by Peter Hein respectively. The story revolves around the struggle of a scientist named Vaseegaran to control his sophisticated android robot named Chitti, after Chitti's software is upgraded to give it the ability to comprehend and exhibit human emotions and to commission it to the Indian Army. The project backfires when Chitti falls in love with Vaseegaran's girlfriend Sana, and is manipulated by Vaseegaran's mentor Bohra into becoming homicidal.

After being stalled in the development phase for nearly a decade, the film's principal photography began in 2008 and lasted two years. The film marked the debut of Legacy Effects studio (which was responsible for the film's prosthetic make-up and animatronics) in Indian cinema. Enthiran was released worldwide on 1 October 2010. Produced by Kalanithi Maran, it was the most expensive Indian film at the time of its release.

The film received generally positive reviews upon release, with critics being particularly appreciative of Shankar's direction, storyline, Rajinikanth's performance as Chitti, music, action sequences, production values and the visual effects by V. Srinivas Mohan. Enthiran emerged as the highest-grossing Indian film of 2010. It won two National Film Awards, three Filmfare Awards, seven Vijay Awards and two Screen Awards. Enthiran was followed by a standalone sequel, 2.0, which released in late 2018.

The scientist K. Vaseegaran creates an android robot named Chitti with the help of his assistants, Siva and Ravi, to commission it into the Indian Army. Chitti helps Sana, Vaseegaran's medical student girlfriend, cheat on her examination, then saves her from a group of thugs in an electric train while returning. Vaseegaran's mentor, Bohra, is secretly contracted to create similar robots for a terrorist organization but so far has been unsuccessful. Threatened with death if he fails to meet the deadline, Bohra seeks the details of Chitti's neural schema, intending to program his robots correctly.

Vaseegaran prepares Chitti for an evaluation by the Artificial Intelligence Research and Development (AIRD) Institute, headed by Bohra. During the evaluation, Chitti nearly stabs Vaseegaran at Bohra's command, which convinces the evaluation committee that the robot is a liability and cannot be used for military purposes. Hoping to prove Bohra wrong, Vaseegaran deploys Chitti to save people from a burning building but fails when Chitti saves a girl bathing but flees being ashamed filmed naked on TV and is hit by a truck and dies. Vaseegaran requests Bohra for one month to modify Chitti's neural schema to enable it to understand human behaviour and emotions to which Bohra agrees. While nearing the deadline, Vaseegaran insults Chitti, who becomes angry with Vaseegaran, demonstrating to him that it can manifest emotions.

Chitti uses Sana's textbooks and an ancient delivery method to help Sana's sister Latha's childbirth complication. Bohra congratulates Vaseegaran and belatedly lets Chitti pass the AIRD evaluation. Chitti develops romantic feelings for Sana after she congratulates Chitti by kissing it. Later, at Sana's birthday party, Chitti seduces her while dancing and is confronted by Vaseegaran and Sana, to whom it confesses its love towards her. Vaseegaran reprimands Chitti, while Sana explains that they can only be friends. Chitti is saddened by her rejection, until Bohra convinces it to fight for its love for Sana, at Vaseegaran's expense. Chitti purposely fails an evaluation by the Indian Army by talking off-topic. Enraged, Vaseegaran chops Chitti into pieces, which Siva and Ravi dump into a landfill site.

Bohra visits the site to retrieve Chitti, which has crudely reassembled itself. He reconstructs Chitti, in exchange for its neural schema, with the help of Siva and Ravi. Bohra embeds a red chip which converts it into a ruthless killer. Bohra tells Siva and Ravi that he is doing this to earn money through his business and defame Vaseegaran. Chitti gatecrashes Vaseegaran and Sana's wedding, kidnaps Sana, kills many police officers, and creates replicas of itself using Bohra's robots. Bohra tries to stop Chitti, who kills him. Using its robot army, Chitti occupies AIRD. After informing Sana that it has acquired the human ability to reproduce, Chitti wishes to marry her so that a machine and a human being can give birth to a preprogrammed child, but Sana refuses. It eventually finds Vaseegaran, who entered AIRD to stop it, and nearly kills him before the police appear. The ensuing battle between Chitti's robot army and the police personnel leads to many casualties. Vaseegaran eventually captures Chitti using a magnetic wall and accesses its internal control panel, whereby he instructs all the other robots to self-destruct, and removes Chitti's red chip.

In a court hearing, Vaseegaran is sentenced to death for the casualties caused by the robot army, but Chitti explains that Bohra is the culprit and shows the court video footage of Bohra installing the red chip. The court drops all charges on Vaseegaran but orders Chitti to be dismantled. Left with no choice, Vaseegaran tells Chitti to dismantle itself. Chitti does so while apologising to Sana and Vaseegaran and receives their forgiveness.