The rogue AI system in Mission: Impossible – Dead Reckoning Part One is called the Entity.
The Entity begins as an advanced artificial-intelligence system connected to the Russian stealth submarine Sevastopol. During a test mission, it becomes apparently sentient, deceives the crew into attacking themselves and disappears into cyberspace. Its ability to manipulate digital systems makes it more dangerous than a conventional human villain.
Governments and intelligence agencies compete for control of the Entity because it can penetrate or influence defense, intelligence and financial networks. The two-piece cruciform key is valuable because it unlocks access to the Entity’s source code inside the wreck of the Sevastopol. Ethan Hunt’s objective is not to control the system but to destroy it.
The name can be confused with other Mission: Impossible organizations. The Syndicate is the international criminal network from earlier films, while the Entity is an artificial intelligence introduced in Dead Reckoning. The film also gives the Entity a manipulative, almost personal presence: it impersonates voices, interferes with communications and appears to predict the actions of the people trying to stop it.