Terminator 2: Judgment Day is a 1991 American science fiction action film directed by James Cameron, who co-wrote the script with William Wisher. Starring Arnold Schwarzenegger, Linda Hamilton and Robert Patrick, it is the sequel to The Terminator (1984) and is the second installment in the Terminator franchise. In the film, the malevolent artificial intelligence Skynet sends a Terminator—a highly advanced killing machine—back in time to 1995 to kill the future leader of the human resistance John Connor when he is a child. The resistance sends back a less advanced, reprogrammed Terminator to protect Connor and ensure the future of humanity.

The Terminator was considered a significant success, enhancing Schwarzenegger's and Cameron's careers, but work on a sequel stalled because of animosity between the pair and Hemdale Film Corporation, which partially owned the film's rights. In 1990, Schwarzenegger and Cameron persuaded Carolco Pictures to purchase the rights from The Terminator producer Gale Anne Hurd and Hemdale, which was financially struggling. A release date was set for the following year, leaving Cameron and Wisher seven weeks to write the script. Principal photography lasted from October 1990 to March 1991, taking place in and around Los Angeles on an estimated $94–102 million budget, making it the most expensive film made at the time. The advanced visual effects by Industrial Light & Magic (ILM), which include the first use of a computer-generated main character in a blockbuster film, resulted in a schedule overrun. Theatrical prints were not delivered to theaters until the night before the picture's release on July 3, 1991.

Terminator 2 was a critical and commercial success, grossing $519–520.9 million at the box office to become the highest-grossing film of 1991 worldwide and the third-highest-grossing film of its time. The film won several accolades, including Saturn, BAFTA, and Academy awards. Terminator 2 merchandise includes video games, comic books, novels, and T2-3D: Battle Across Time, a live-action attraction.

Terminator 2 is considered one of the best science fiction, action, and sequel films ever made. It is also seen as a major influence on visual effects in films, helping usher in the transition from practical effects to reliance on computer-generated imagery. The United States Library of Congress selected it for preservation in the National Film Registry in 2023. Although Cameron intended for Terminator 2 to be the end of the franchise, it was followed by a series of sequels, including Terminator 3: Rise of the Machines (2003), Terminator Salvation (2009), Terminator Genisys (2015), and Terminator: Dark Fate (2019), as well as a 2008 television series.