Cyborgs

Cyborgs are a group of half-human and half-machine robots that appeared in the fourteenth Give Yourself Goosebumps book, The Creepy Creations of Professor Shock.

The Creepy Creations of Professor Shock
In one of the good endings, Stacey and Jason reveal themselves and Uncle Jack to be cyborgs, having used the reader to acquire the remote from Professor Shock. As a reward for helping the cyborgs take over earth, they offer to make the reader a cyborg as well. It is implied that the reader actually becomes a cyborg.

Goosebumps 2: Haunted Halloween
A female cyborg appears in the movie Goosebumps 2: Haunted Halloween as a Halloween mask brought to life by Slappy the Dummy.