The film opens with the depiction of the year 2029—a possible future where mankind has been oppressed by artificially intelligent machines, lead by the rebellious computer system Skynet. This computer became sentient and started a nuclear war by hijacking control of the United States' nuclear arsenal, launching the ICBM's in a devastating attempt to annihilate humanity. Now a post-apocalyptic war is raged in the future, where a small Resistance group of free humans try to win back their planet and survive the machine onslaught, lead by the heroic, influential General John Connor: the man responsible for the creation of the human resistance, and credited with rescuing mankind from extinction by rallying survivors to try and combat Skynet's forces.
A scroll appears on the screen, stating "The machines rose from the ashes of the nuclear fire. Their war to exterminate mankind had raged on for decades. But the final battle will not be fought in the future, it would be fought in our present...tonight."
Though the year is not specifically mentioned, the "present day" of the movie starts in the year 1984, Los Angeles, and introduces the arrival of the Terminator, a Series 800 Model 101 Infiltrator unit sent back in time by Skynet to assassinate Sarah Connor, mother of the future savior of mankind (and Skynet's greatest enemy), before he is conceived by an unknown father the following year. T-800 Model 101 Infiltrator Unit. NooBiBoyAdded by NooBiBoy
The Terminator arrives nude because of the time machine being powered by organic matter, so that clothes, weapons, etc. can't be sent back. The cyborg assassin is able to travel due to it being a skeletal robot covered by living human skin, protecting the combat chassis and metal endoskeleton underneath. The T-800 steals clothing from three reckless punks (one played by Bill Paxton), and then after stealing a large amount of deadly weaponry, begins to systematically hunt down and murder every person listed as "Sarah Connor" in the phone book, in alphabetical order, to guarantee no mistakes with identity.
Meanwhile, in another part of town, human resistance soldier Kyle Reese has arrived through time as well, tasked with protecting John Connor's mother from the Terminator, which was sent back as a last-second act of desperation by Skynet to eliminate its enemy's entire existence. He steals clothes from a derelict bum, and steals a shotgun from a police vehicle. The Terminator's systematic murder of the three women listed as “Sarah Connor” in the vicinity draws media attention and the notice of police Lt. Ed Traxler (Paul Winfield), and detective Hal Vukovich (Lance Henriksen). The real Sarah Connor, a hapless waitress with a dull life and living with her best friend and roommate Ginger Ventura, finds out about the murders on television, and, worried by the name connection, takes shelter in a nightclub, TechNoir, to wait for police protection.
While there, the Terminator and Reese both arrive to acquire her, and thankfully Reese saves the innocent, defenseless Sarah from the murderous cyborg. Fleeing in a stolen vehicle with the Terminator in pursuit with a hijacked police car, Kyle tells the terrified woman what is going on, to her initial disbelief. After an intense shootout between Reese and the attacking Terminator, the authorities capture the duo and bring them to the LAPD police station. The Terminator escapes unseen, and breaks into a hotel room to perform self-repairs on its damaged eye and right arm, having to cover the former with sunglasses.
At the police station, Sarah is reassured by criminal psychologist Peter Silberman, who believes that Reese is an insane, delusional "loon." His claims about the future and the advanced robot's mission are dismissed as those of a raving lunatic. They also have the "logical explanations" about the terminator; they think he survived tons of bullets with a bullet-proof vest and that when he smashed through a window with his bare hands, he must have broken every bone in his arm.
However, mere minutes later the Terminator arrives at the station, and when denied access to see Sarah, casually utters "I'll be back", before driving a car right into the lobby. The machine begins a one-man assault on the station, slaughtering seventeen police officers in its determined search. Reese and Sarah are able to escape once again, and go into hiding. They rent a room at the Tiki Motel, where Reese begins teaching Sarah how to build homemade explosives.
During their night at the motel, Sarah and Reese discuss their feelings, where Sarah expresses her disbelief and feeling of shame at being the mother of mankind's only hope. She doubts Reese's account of Sarah being thought of as a legendary warrior in his future, and says he must be disappointed. He quietly denies this, saying that he was given a picture of Sarah by Connor himself for good luck, and that he fell deeply in love with the woman in the photo. Admitting his passionate feelings for Sarah, who is deeply touched, Kyle thinks he has made a fool of himself and tries to stay cool... until Sarah reciprocates his desire, and the two make love.
Later, as Sarah and Kyle get dressed, they hear the sound of barking dogs; the Terminator has found them. Sarah and Reese flee in a truck as the T-800 chases on a motorcycle. During this chase Kyle is mortally wounded by a gun shot from the Terminator. In rage, Sarah rams the motorcycle, causing both her and the machine to get into a violent crash. The T-800 commandeers a massive tanker truck, and tries to drive over Sarah, while the injured Reese tosses a homemade pipe bomb into the exhaust of the vehicle. The resulting explosion destroys the tanker, and the Terminator limps through the rubble as its synthetic human flesh covering completely burns away, revealing the gleaming metal cyborg endoskeleton beneath. The monstrous robot continues to chase Sarah and Reese on foot into a hydraulics facility, where Reese, in a valiant effort to stop the machine, first struck it with a metal bar, receiving more fatal blows as the machine retaliated with a back-handed swipe. Kyle manages to blow apart the robot's torso by inserting another homemade pipe bomb among the hydraulic components in the abdomen, destroying the lower half and unintentionally killing himself and injuring Sarah in the leg due to debris from the blast.
The T-800's upper torso is still operational, and begins to crawl after Sarah, who was hampered by her injured leg. She climbs behind a metal slide-gate, which the Terminator tries to reach its arm through the bars to strangle her. With the T-800 distracted, Sarah then presses the button—she had lured the machine under a hydraulic press. As she reaches for the start button, Sarah taunts the Terminator with the phrase, "You're terminated, fucker!" The Terminator is crushed to oblivion by the press, and Sarah's life is saved.
The screen then jumps forward, showing the aftermath of the film's events. Sarah is now pregnant with a boy, revealing the movie's twist: by sending back a protector for his mother, John Connor actually inadvertently created his own existence. In their romantic night together, Reese had conceived a child with Sarah, paradoxically becoming John's father. She acknowledges this during a recording she has taped to later give to her son at the proper age.
Sarah then stops at a gas station in Mexico on November 10, 1984 (she has now become a fugitive from society), where she has a photograph taken of herself before departing. In a final twist of fate, the audience sees that this is exactly the same picture that Kyle Reese carries in the future. Sarah then drives off into the distance to train her son in preparation for his destiny and in the distance, storms are approaching over the mountains. The end credits start to roll as her Jeep disappears.
- Arnold Schwarzenegger as The Terminator, a cyborg sent back in time to assassinate Sarah Connor.
- Michael Biehn as Kyle Reese, a human Resistance fighter sent back in time to protect Sarah.
- Linda Hamilton as Sarah Connor, the Terminator's target.
- Franco Columbu as Future Terminator
- Earl Boen as Dr. Silberman, a police psychologist.
- Paul Winfield as Ed Traxler, a police Lieutenant who questions Sarah.
- Lance Henriksen as Hal Vukovich, a police Detective who questions Sarah.
- Writer/director James Cameron provided the voice breaking his date with Linda Hamilton on her message machine. Cameron would later marry and divorce Linda Hamilton.
- The life-size Terminator model was actually made of steel, a production error that complicated the film's shooting. The model was so heavy that it required four people to hold it and move it during close-ups.
- In 2003, The American Film Institute released its list of the 100 greatest screen heroes and villains of all time. The Terminator appeared as number 22 on the list of villains. He also appeared at number 48 on the list of heroes (for subsequent roles).
- Schwarzenegger's famous line "I'll be back", which originated from The Terminator, was originally written as "I'll come back".
- Bill Paxton and Lance Henriksen are the only two actors to play characters killed or injured by a Terminator, an Alien and a Predator. Paxton was killed in The Terminator, Aliens and Predator 2, while Henriksen was killed in The Terminator, ripped in two (as an android) in Aliens and killed by a Predator in Alien vs. Predator.
- Every film in the Terminator series has a chase scene featuring a truck. The Terminator and Terminator 2: Judgment Day both have scenes in a parking garage.
- When the Terminator traces Sarah Connor to the motel just after the love scene, the eye-vision of the Terminator is displayed. There are several printouts of assembly code from the MOS Technology 6502 microprocessor.
- In the UK, The Terminator was originally rated as a 18. When the film was released to DVD, it was re-rated to a 15. In Germany, the uncut version is still rated as a 18 and on Germany's legal child-welfare index.
- The original script had another soldier sent back with Reese to protect Sarah, but the other soldier, called "Sumner", was cut from the final script. He would not have received much screen time, as he died upon arriving, fused into a fire escape by the time displacement field. This contradicts what the sequels show of the time displacement field simply melting whatever is in its path.
- The original screen treatment and drafts gave Reese's age as 21 or 22 while Sarah's age was only 19. In real life, actors Michael Biehn and Linda Hamilton were both 27. The second Terminator film gave Sarah's age at the time of her attack as 19, while the third indicated that she was 25.
- In the original script, the Terminator had to eat in order to maintain its organic flesh. After killing the first wrong Sarah Connor, the Terminator was shown eating a candy bar - complete with the wrapping.
- The original script said that Sarah had a pin in her knee from an old skating accident. The Terminator would then go about mutilating its victims in order to find this identifying pin. The novelisation reveals Sarah had to have pins inserted into her leg as a result of shrapnel damage caused by destroying the Terminator, creating the very identifying mark it was looking for, when it mutilated the other victims' legs.
- Although playing the title character, Arnold Schwarzenegger has only 58 spoken words in the film (the Terminator also has more sentences in Sarah Connor's mother voice, but they are said off-screen and it is only discovered that it is the cyborg in the last one).
- Franco Columbu makes a cameo appearance as a Terminator in the future in one of Kyle Reese's dreams. This Terminator also appears in the Terminator 3 video game as a boss character.
- The scene where the Terminator endoskeleton is chasing Sarah through the factory after having its lower torso blown away was #82 on Bravo's 100 Scariest Movie Moments.
- Kyle and the Terminator were sent back in time to Thursday, May 12, 1984. However, the 12th did not fall on a Thursday in 1984, but in the previous year, 1983.
- A common bit of misinformation states that Brad Reardon played the Unnamed Punk who was left from the credits. However, this role was actually played by New York actor David Kristen. He was kept from the credits after an argument on set with Cameron.
- Originally the Terminator was supposed to look like an average man, someone who could blend into a crowd. An actor they wanted to play this version was former NFL player and movie actor O.J. Simpson. James Cameron passed over O.J. because he "...couldn't imagine such a nice guy playing the part of a ruthless killer".
- Arnold's nude body-double for this movie, Peter Kent, was cast and appeared as "Melvin" the first morgue corpse brought back to life in H.P. Lovecraft's Re-Animator, filmed concurrently with The Terminator.
- James Cameron, Michael Biehn, and Arnold Schwarzenegger are all Leos. Not very noteworthy, but an interesting fact.
- The Terminator, originally thought of as a low-budget exploitation film that would make a minor buck or two, opened to surprisingly great numbers, generating millions at the box office and becoming one of the top hits of 1984. Critics were caught off-guard by the detailed plot and complexity of the characters' relationships, and subsequently lathered the film with stellar reviews. Many even placed The Terminator on their "Top Ten Best of..." lists.
- The Terminator character, played by former bodybuilder and upcoming actor Arnold Schwarzenegger, instantly became a pop-culture icon, and arguably the most (in)famous movie character of all time. Overnight, lines such as "I'll be back" and "Sarah Connor?" (best when spoken with a thick, baritone imitation of Schwarzenegger's Austrian accent) became integral to the teenage and sci-fi geek vocabulary, and Schwarzenegger gained everlasting fame for his portrayal of the character. Schwarzenegger would later go on to reprise the role (albeit with a few creative differences) in the two sequels, Terminator 2: Judgment Day and Terminator 3: Rise of the Machines, arguably becoming the top action hero star of the 80's and early 90's.
- The Terminator has an rating of 100% "fresh" reviews at the critic aggregator website, Rotten Tomatoes.com.
- The Terminator is honored with a spot on the "IMDb Top 250".