Velayudham (/veɪlɑːjʊðəm/) is a 2011 Indian Tamil-language superhero film directed by M. Raja, who co-wrote the screenplay with R. T. Neason, while the dialogues were written by the duo Subha. Produced by V. Ravichandran, it stars Vijay in the title role with Genelia D'Souza and Hansika Motwani, while Santhanam, Saranya Mohan, Soori, Abhimanyu Singh, and Vineet Kumar play prominent roles. In the film, a journalist tracks down a villager who had unknowingly foiled a terrorist plot and persuades him to embrace his heroism as a symbol of hope for the people.

Velayudham was inspired by the 2000 Telugu film Azad; Raja obtained permission to remake the film but eventually retained only the premise. Filming began in July 2010 and continued till September 2011, lasting 150 working days; filming primarily took place in Pollachi and Udumalaipettai for the village portions, while rest of the action and song sequences were filmed in Chennai, Hyderabad, Odisha, Kochi and Kashmir. The music was composed by Vijay Antony with cinematography by Priyan and editing by B. Lenin and V. T. Vijayan.

Velayudham was released on 26 October 2011 coinciding with Diwali and became a commercial success. Amongst its accolades, the film won two Edison Awards and an Ananda Vikatan Cinema Award, while being nominated for a South Indian International Movie Award and two Vijay Awards.

Bharathi, a young journalist, and her two friends investigate a series of terrorist attacks which have taken place in Chennai and also other illegal activities like human trafficking. One night, Bharathi and her friends are caught video-recording illicit activities happening in a secluded house by a group of thugs, where they attempt to flee from them. While Bharathi's friends are murdered, Bharathi manages to escape despite being stabbed by one of the thugs. After the attack on Bharathi and her friends, the thugs' vehicle explodes due to a small mishap when a cigarette falls over petrol packets stored in the vehicle, killing the thugs.

Bharathi comes up with a new idea to eradicate society's evils by creating and propagating a fictitious character called "Velayudham" (after seeing a Murugan temple nearby) who wants to clean up the city of terrorism and other illegal activities. Meanwhile, in a village named Pavunoor. Velayudham "Velu" is a milk vendor who lives with his younger sister Kaveri and niece Vaidehi, unaware that she likes him as a future husband. One day, Velu, Kaveri, and Vaidehi leave for Chennai to collect money from a chit fund for Kaveri's marriage. At the Chennai Egmore railway station, Velu's handbag is stolen by Speedu, a petty thief. Velu pursues Speedu on a motorbike parked at the station and manages to get back his money. Moments after alighting from the bike, the bike explodes.

The parked bike had a bomb which was meant to ensure a terrorist attack at the railway station, which Velu inadvertently thwarted. Velu unknowingly prevents more terrorist attacks and comes to Bharathi's attention. At first, Bharathi hates him due to various incidents, but when she sees him unknowingly handing over the terrorists to the police, she falls in love with him without knowing that Vaidehi also loves him. When Bharathi learns that Velu unknowingly prevented the attacks, she convinces him to take up the role of Velayudham and provide hope for the people, but Velu refuses and tells her to finish the avatar of Velayudham.

Later, Velu learns that his money is stolen and the company where he insured the money was a corrupt company. The people get enraged when they learn that their money was stolen. One of them commits suicide by burning himself alive. When the villagers tells that Velayudham will come and help them, Velu plans to take the role of Velayudham and kills the person who stole the people's money and returns the money to the people. In the avatar of Velayudham, Velu starts to eradicate society's evils among others, where he soon gains wide support and acceptance among the public and police.

A few months later, Velu returns to Pavunoor with Bharathi for Kaveri's marriage. Unknown to Velu, Musafir Ibrahim, the leader of a terrorist group followed him to his village. Ibrahim wants to kill Velu since he thwarted every terrorist attack that he had planned in Chennai. On the day of Kaveri's marriage, a bomb planted by Ibrahim at Velu's house explodes, killing Kaveri. Velu later learns from Bharathi that the corrupt Home Minister Ulaganathan is indirectly responsible for the terrorist attacks and Kaveri's death.