Thani Oruvan (transl. The Sole One) is a 2015 Indian Tamil-language action thriller film directed by Mohan Raja and written by Raja and Suresh and Balakrishnan. Produced by Kalpathi S. Aghoram, S. Ganesh and S. Suresh under the studio AGS Entertainment, it stars Jayam Ravi, Arvind Swamy and Nayanthara while Ganesh Venkataraman, Harish Uthaman, Nassar, Thambi Ramaiah, Mugdha Godse, amongst others play supporting roles.

The plot revolves around IPS Officer Mithran, who wants to arrest Siddharth Abhimanyu, an affluent scientist who uses secret illegal medical practices for profit. Thani Oruvan was Raja's original story concept, unlike his previous ventures, which were remakes. Principal photography commenced on 6 December 2013, with filming took place in various locations including Chennai, Bangalore, Hyderabad, Dehradun, Mussoorie, and other locations.

The cinematography and editing were handled by Ramji and Gopi Krishna respectively. The music was composed by Hiphop Tamizha, in which the soundtrack album received positive reviews. The film was released on 28 August 2015, to critical acclaim, with critics praising the performances of Jayam Ravi and Aravind Swamy, especially the latter and also Thambi Ramaiah, pace, screenplay, storyline & direction. It was a commercial success, and also became one of the highest grossing Tamil films of the year.The film was remade in Telugu as Dhruva (2016), and in Bengali as One (2017). After 8 years following the huge success of the film, Mohan Raja announced the sequel, Thani Oruvan 2, reuniting with Ravi and Nayanthara.