What is the model designation of the Terminator sent to protect John Connor in Terminator 2?

The protector in Terminator 2: Judgment Day is a reprogrammed T-800 Model 101.

The machine is sent from the future by the human resistance to protect the young John Connor. Arnold Schwarzenegger portrays the character, whose endoskeleton is covered by living tissue that allows it to resemble a human. Its mission places it in direct conflict with the T-1000, a more advanced infiltrator made from mimetic polyalloy.

“T-800” identifies the Terminator's machine series, while “Model 101” refers to the human appearance associated with Schwarzenegger's version. The film also uses the name Cyberdyne Systems Model 101 in related descriptions, which is why the designation is often shortened in conversation.

The T-800 is not the same model as the T-850 seen in Terminator 3. The protector's reprogrammed role is also different from the murderous T-800 sent after Sarah Connor in the original film.