Avatar is a 2009 American epic science fiction film written and directed by James Cameron, and starring Sam Worthington, Zoe Saldana, Stephen Lang, Michelle Rodriguez, Joel David Moore, Giovanni Ribisi and Sigourney Weaver. The film is set in the mid-22nd century, when humans are mining a precious mineral called unobtanium on Pandora, a lush moon of a gas giant in the Alpha Centauri star system. The expansion of the mining colony threatens the continued existence of a local tribe of Na'vi—a humanoid species indigenous to Pandora. The film's title refers to the genetically engineered Na'vi-human hybrid bodies used by a team of researchers to interact with the natives of Pandora.

Development on Avatar began in 1994, when Cameron wrote an 80-page scriptment for the film. Filming was supposed to take place after the completion of Cameron's 1997 film Titanic, for a planned release in 1999, but according to Cameron, the necessary technology was not yet available to achieve his vision of the film. Work on the language for the film's extraterrestrial beings began in summer 2005, and Cameron began developing the screenplay and fictional universe in early 2006. Avatar was officially budgeted at $237 million. Other estimates put the cost between $280 million and $310 million for production and at $150 million for promotion. The film was released for traditional 2-D viewing, 3-D viewing (using the RealD 3D, Dolby 3D, XpanD 3D, and IMAX 3D formats), and "4-D" viewing. The stereoscopic filmmaking was touted as a breakthrough in cinematic technology.

Avatar premiered in London on December 10, 2009, and was internationally released on December 16 and in the United States and Canada on December 18, to critical acclaim and commercial success. The film broke several box office records during its release and became the highest-grossing film of all time in the U.S. and Canada and also worldwide, surpassing Titanic, which had held the records for the previous 12 years. It also became the first film to gross more than $2 billion. Avatar was nominated for nine Academy Awards, including Best Picture and Best Director, and won three, for Best Cinematography, Best Visual Effects, and Best Art Direction. The film's home release went on to break opening sales records and became the top-selling Blu-ray of all time. Following the film's success, Cameron signed with 20th Century Fox to produce two sequels, making Avatar the first of a planned trilogy.