Terminator 2: Judgment Day (also promoted as T2) is a 1991 American science fiction action film produced and directed by James Cameron, who co-wrote the script with William Wisher. It stars Arnold Schwarzenegger, Linda Hamilton, Robert Patrick, Edward Furlong, and Joe Morton. It is the sequel to the 1984 film The Terminator, and the second installment in the Terminator franchise. It follows Sarah Connor (Hamilton) and her ten-year-old son John (Furlong) as they are pursued by a new, more advanced Terminator: the liquid metal, shapeshifting T-1000 (Patrick), sent back in time to kill John and prevent him from becoming the leader of the human resistance. A second, less-advanced Terminator (Schwarzenegger) is also sent by the Resistance to protect John.

Talks of a follow-up to The Terminator arose following its release, but its development was stalled due to technical limitations of the vital computer-generated imagery, and legal issues with original producer Hemdale Film Corporation, who controlled half of the franchise rights. In 1990, Carolco Pictures acquired the rights from Hemdale and production immediately began, with Schwarzenegger, Hamilton, and Cameron returning. Principal photography began in October 1990 and lasted until March 1991. Its visual effects saw breakthroughs in computer-generated imagery, including the first use of natural human motion for a computer-generated character and the first partially computer-generated main character. At the time of its release, with a budget of $94–102 million, Terminator 2: Judgment Day was the most expensive film ever made.

Terminator 2: Judgment Day was released in the United States on July 3, 1991 by TriStar Pictures. It was a critical success upon release, with praise for the acting, action scenes, and visual effects. Regarded as superior to the original and one of the best sequels ever made, the film influenced popular culture, especially the use of visual effects in films. It grossed $520 million worldwide, becoming the highest-grossing film of 1991 and of Schwarzenegger's career. It received several accolades, including Academy Awards for Best Sound Effects Editing, Best Sound, Best Makeup, and Best Visual Effects, and the Hugo Award for Best Dramatic Presentation - Long Form.

Other films followed: two sequels, Terminator 3: Rise of the Machines in 2003 and Terminator Salvation in 2009; a reboot, Terminator Genisys in 2015; and the Cameron-produced film Terminator: Dark Fate in 2019 which was intended to be an alternate sequel and retcon from Rise of the Machines onward. A sequel television series, Terminator: the Sarah Connor Chronicles, ran from 2008 to 2009. In 2017, Terminator 2 was re-released in 3D 4K resolution for AMC and Cineplex theaters, and internationally, debuting at number one in the United Kingdom on its release weekend.