Demon) is a 2016 Indian Tamil-language psychological action thriller film[2] written and directed by Pradeep Krishnamoorthy in his directoral debut .

The film stars Vijay Antony in a dual role as father and son with Arundhati Nair, Charuhasan, Y. G. Mahendra, Siddhartha Shankar and Kitty amongst others forming the secondary cast.

by Sujatha,[3] it revolves around a software engineer who gets into trouble after he starts hearing strange voices asking him to kill a woman named Jayalakshmi.

It is revealed that Dinesh had been recently married to a orphan Aishwarya (Arundhati Nair), who had contacted him through a matrimonial site.

Upon investigating, he finds a picture of Sharma (Vijay Antony in his previous life) was a respected bachelor who adopted a boy Gopal and later married Jayalakshmi (Arundhati Nair).

Two weeks later, both Sharma and Gopal are found dead on the banks of a river and Jayalakshmi, Nataraj, are absconding.

He is sedated and left inside his room for a few days, where Sharma refuses to accept leave Dinesh's body.

Thomas calls up Dinesh and asks him to bring back the shreds of evidence that were stolen from his guest house.

This causes him to get extra ordinary power while his body is taken over by Sharma, and he takes down everyone and heads to finish Aishwarya.

In June 2014, Vijay Antony announced that he was working on a project titled Saithan, which would begin after the completion of his impending films.

[4] Bike racer Alisha Abdullah also revealed that she would be a part of the film during an interview in October 2014, stating that it was a psychological thriller and based on the novel, The Girl with the Dragon Tattoo.

[8] Arav, who later became popular with the show Bigg Boss, made his acting debut with this film, and had no lines of dialogue.

Vijay Antony came up with a unique promotional strategy by releasing the first 5 minutes of the film as sneak peek.

[10] When the makers initially launched the teaser of Saithan with the theme song penned by late lyricist Annamalai, few Hindu groups have raised objections to the using of Sanskrit slokas in the background music of the film.