16 Vayathinile (transl. At Age 16; read as Pathinaaru Vayathinile) is a 1977 Indian Tamil-language romantic drama film co-written and directed by Bharathirajaa in his directorial debut. The film stars Kamal Haasan, Sridevi, and Rajinikanth, with Ganthimathi, Sathyajith and Goundamani in supporting roles. It focuses on the strengths and vulnerabilities of Mayil (Sridevi), a 16-year-old schoolgirl, and the challenges she faces and overcomes.

The film was originally titled Mayil, and set to be funded by the National Film Development Corporation of India. When they backed out, it was picked up by S. A. Rajkannu who produced it under his banner Shri Amman Creations, and eventually retitled. 16 Vayathinile became the first Tamil film to be shot predominantly outdoors; Tamil films were primarily filmed in Madras studios. Its soundtrack album and background score were composed by Ilaiyaraaja, with cinematography by P. S. Nivas. P. Kalaimani wrote the film's dialogue.

16 Vayathinile was released on 15 September 1977, and was distributed by Rajkannu himself since no distributor was willing to buy it. Although written off by the media as an experimental film that would fail, the film received critical praise for Bharathiraja's script, Ilaiyaraaja's music and the performances of Haasan, Sridevi and Rajinikanth. It was commercially successful, with a 175-day theatrical run. It won numerous awards, including the National Film Award for Best Female Playback Singer for S. Janaki; the Filmfare Award for Best Actor (Tamil) for Haasan and Special Commendation Award for Performance for Sridevi; and four State Awards, including Best Director for Bharathiraja and Best Actor for Haasan.

16 Vayathinile attained cult status in Tamil cinema and is considered to be the bellwether of films depicting realistic portrayals of rural life. Making stars of its director and lead actors, it was remade in Telugu as Padaharella Vayasu (1978), in Hindi as Solva Sawan (1979), and in Malay as Melati Putih (1984).