Katherine (Kathy) Martinez is the pregnant wife of 2nd Lieutenant William Martinez, who died during the Battle of Los Angeles when he sacrificed himself to destroy an alien air unit. When William left to go into battle against the aliens, he wrote a note to Kathy when he expected the worst. He had given the note to Michael Nantz, the staff sergeant of his platoon, to give to Kathy. Nantz then gave it to Michele, one of the civiians he rescued from the battle. It is unknown if Kathy survived the battle, but she is assumed to have survived. It is unknown if her child was ever born either.
- Kathy had a very minor role in the film.
- Originally, she was named Anna Martinez.
- When Staff Sergeant Michael Nantz gave the letter from Lieutenant Martinez to Michele to give to Kathy, this may have meant that Michele and Kathy had known each other in some way not mentioned in the film.
- She was portrayed by Elizabeth L. Keener.