Koi... Mil Gaya is a 2003 Bollywood science fiction film directed by Rakesh Roshan (who also has a cameo role), starring Hrithik Roshan, Rekha and Preity Zinta. The film's theme is largely inspired by the 1982 Hollywood hit E.T. the Extra-Terrestrial, which was also accused of being inspired of the cancelled movie The Alien written by Indian director Satyajit Ray, although the director has claimed that it is 'not an Indian E.T.

The film was released on 8 August 2003. It was shot in Kasauli, Nanital, Bhimtal and in Canada.

Koi... Mil Gaya was the most successful Bollywood film of 2003 and swept the Best Picture, Best Director (Rakesh Roshan) and Best Actor (Hrithik Roshan) awards in all major award ceremonies of 2003 including the Filmfare Awards, IIFA Awards,Screen Awards, etc. It is widely regarded as Bollywood's very first sci-fi thriller. It spawned two sequels — Krrish and Krrish 3 — making it the first of the Krrish film series. It also spawned a spin-off animation-cum-live-action series titled J Bole Toh Jadoo that aired on Nickelodeon (India).

The film was screened at the Jerusalem Film Festival and the NatFilm Festival in Denmark.