Until her death, Marilyn Siegel was a doctor at Mercy Hospital in Toronto. The character appeared in only one episode, "Last Act", and was played by Gillian Vanderburgh. After losing a patient in the emergency room, Dr. Siegel goes into the locker room with another colleague, Dr. Cole. As she is changing, she describes how useless she feels not having been able to save the patient. Her friend comforts her by massaging her shoulders and reminds her of what one can and cannot do as a doctor. A short while later, she is in the shower when she is surprised and killed by an intruder whom she apparently knows, but is not expecting to see.