Terminator (850 Series, Model 101)

"That was a different T-101"

The Terminator explaining to John that this is a different Terminator

This Cyber Research Systems Model 101 Series 850 Infiltration-Combat Unit was sent back in time from 2032 to 2004 by Kate Connor to protect her younger self and her future husband,John Connor.

Personality
Although physically similar to the T-800, the T-850 possesses a number of noticeable differences; The T-850's appearance is an aged version of the T-800 and lacks the sense of humor exhibited by its predecessor. It almost seems to stand up for itself when it replied that it is a "cybernetic organism", not a "Robot", as John had stated. Although originally programmed to follow any and all orders from Kate, it could override this default programming and trap her in the back of her truck against her wishes. It states that one of its basic subroutines deals with human psychology, and despite its lack of humor is still able to make an emotional connection with John when he fights the T-X's reprogramming of his systems and again later when he says goodbye to John.

Terminator 3: Rise of the Machines
When it emerged from its time displacement sphere in Joshua Tree, California, it went to a club to acquire its clothing and then proceeded steal a truck and got sunglasses.

It approached Connor in a veterinarian clinic where Brewster worked and took the two with him in the back of a van to escape the T-X sent to kill them. While driving, John asked him about its memories, assuming that this would have the same memories as "Uncle Bob". It stated that the Terminator sent from last time was a different unit and he was chosen by Skynet for infiltration due to John's emotional attachment.

At a graveyard, the three went to Sarah Connor's grave. The Terminator dropped her coffin to find weapons inside. When the police arrived, they got out and confronted the T-X. Later, at a campsite, the Terminator revealed that if the T-X failed to kill John and Kate, it would kill John's future officers as secondary targets, including Kate's father, Robert Brewster. While driving, the Terminator revealed that it was Katherine who sent the machine from the future, not John, because the Terminator killed John before being captured and reprogrammed by Kate.

In the Cyber Research Systems facility, the Terminator battled with T-1 units. It also fought the T-X, but lost. Controlled by the T-X, the T-850 began to attack John and Kate, but shut itself down to prevent itself from killing John. Later it rebooted, regained control of itself, and again battled the T-X at Crystal Peak. It managed to detonate its last hydrogen fuel cell to destroy itself and the T-X.

Note: ''It is seen during John's narrative at the end, with only its head still intact and online. As the viewer watches, its eyes fade and it "dies". ''