Marjorie's Not Here (The Fire)

The reason we've been able to name the mysterious gray haired lady is due to one of the only on screen, dialogued mentions of her presence by Dwight K. Schrute.

In the episode The Fire, Dwight says about Ryan, regarding the workers counting off during the fire drill:

"He can have #14, Marjorie's not here today."


And after close repeated scrutiny of this episode, we've decided that she's nowhere to be seen standing around outside. So unless Marjorie actually tampered with the toaster oven, and was the true originator of the fire, and hid from the authorities and her fellow workers ... she was indeed absent on that particular day.