Machines can be reprogrammed to follow the commands of someone other than its original creator, usually Skynet. This ability is used by the Resistance to reprogram Terminators, and by Terminators to reprogram other Terminators.
The Resistance used humans skilled in programming to reprogram Terminators, such as Danny Dyson.
The T-X had the ability to use nano-bots to reprogram and control machines and Terminators alike.
Reprogramming can be unreliable. Sometimes a reprogrammed Terminator will "go bad"; a reprogrammed Terminator in the Future War inexplicably went rogue and killed many Resistance fighter in a bunker , and Cameron tried to kill John Connor after her chip was damaged.
Known Reprogrammed Terminators
- C890.L in The Terminator: Secondary Objectives.
- T-800 in Terminator 2: Judgment Day
- T-800 in T2 3-D: Battle Across Time
- Eve and two T-1000 in Terminator 2: The New John Connor Chronicles
- T-850 in Terminator 3: Rise of the Machines
- T-950 in Terminator 3: Fragmented
- Eliza in Terminator Hunt
- Uncle Bob in Terminator: Infinity
- Cameron in Terminator: The Sarah Connor Chronicles
- The Rogue in Terminator: The Sarah Connor Chronicles
- Queeg in Terminator: The Sarah Connor Chronicles episode "Today Is The Day, Part 1" "Today Is The Day, Part 2"
- Moto-Terminator in Terminator Salvation
- Guardian in Terminator Genisys
- After a while, Skynet added a self-destruct to Terminator chips upon chip removal, so that Terminators couldn't be reprogrammed, such as Rosie.
- Some Resistances fighters greatly disliked being surrounded by reprogrammed "metal" all the time. 
- They also sometimes had problems taking orders from reprogrammed metal, such as some of the crew under Captain Queeg on the USS Jimmy Carter.
- Some Resistance fighters didn't like John separating himself from other humans, and only spending time with Cameron. This caused Jesse Flores to go back in time to attempt to alienate John Connor by framing Cameron for the murder of Riley Dawson.
- Reprogrammed Terminators were sometimes referred to by Resistance fighters as "scrubbed". 
- In Terminator Genisys, Guardian was reprogramed and sent back by an unknown party who purposefully erased all of knowledge of their identity from Guardian's mind so that no one else would know who they are and Skynet couldn't find out who they were and stop them.
- Cameron: (referring to a reprogrammed terminator who went rogue) Sometimes they go bad. No one knows why.
- Terminator: The Sarah Connor Chronicles, "Dungeons & Dragons"