Shadow Rachel is a secret antagonist in Those Nights at Rachel's who only attacks the player rarely when they turn towards the back-room while in the office. The chance of seeing it is not affected by which direction the player turns from or how often they check, although it seems to be slightly more active in Hard Mode. Shadow Rachel will appear in front of the player in a silent jump-scare as they turn and move to the right or away from the player slightly before suddenly fading out and vanishing. It's attack is meant mainly to startle and distract the player as so to let the other animatronics get closer. However, it has been reported to rarely crash the game. Shadow Rachel cannot appear when the power runs out, and is never present in the Night 5 cut-scene.
- The Shadow Rachel = Previous Night Guard Theory: It is believed that Shadow Rachel is one of the night-guards Phone Guy mentions on Night 2 as not "getting through" his shift. He mentions a guard who went out of the office to investigate the animatronics' movement, and implies he was either severely injured or killed. If he died, especially if by Rachel, he would have become a ghost who would watch and warn future guards by observing them behind their back in the office. This would also make Shadow Rachel male, and a ghost rather than an animatronic. It is sometimes thought that Shadow Rachel only appears when the player spends too much time in the monitors, and that he gets slow in reacting or vanishing when the player turns and sees them.
- The Shadow Rachel = Adam theory. This theory states that Shadow Rachel may be the child attacked at Freddy Fazbear's Pizza in the week the current guard is playing. The second night's newspaper clipping debunks this, however, as the child is reported alive and safe.
- Shadow Rachel may be in the washroom when not seen by the player, explaining why that camera is always disabled.
- Shadow Rachel's appearance does not change in Hard Mode; it is the only character to still have white eyes and teeth in that mode while the other six animatronics have red eyes and teeth.