Ginger Ventura (portrayed by Bess Motta) was Sarah Connor's roommate in The Terminator. She and her boyfriend Matt Buchanan were killed the night of May 13, 1984, when the Terminator came to their apartment looking for Sarah.
Because most records were destroyed during the Judgment Day, the T-800 had no way to identify Sarah. This was evident due to the T-800 stealing a phonebook page and murdering every lady with the name of Sarah Connor, starting with his termination of Sarah Ann Connor. Due to the T-800's guesswork, it had likely concluded that by murdering Ginger, it had completed its mission to terminate Sarah Connor.
After the Terminator had killed Ginger, Sarah called and their answering machine allowed him to know he hadn't killed Sarah Connor. After finding Sarah's ID, he then had an image of the "real" Sarah Connor, and proceeded to hunt her only.