Character Profile
Portrayed By
Denise Crosby
Season One
First Appearance
Popping Cherry
Last Appearance
Popping Cherry
Full Name
First Nurse
Last Nurse
Manner of Death
Killed by Dexter Morgan on Harry Morgan's orders
45 (at death)
Personal Status
Professional Status
Killer Profile
"No Known Alias"
Number of Victims
At least 5
Modus Operandi
Killing Method
Injecting victims with too much Morphine, causing them to overdose and die. She then collects their obituaries as trophies in a scrapbook.
Method of Disposal
Mary leaves her victims' to die from the drug overdose.
Mary believed that she was easing her victims' worldly sufferings.

Mary, aka the First Nurse, is a character in DEXTER. She worked as a nurse at a hospital, and eventually began poisoning her patients under the delusion that she was "taking their pain away." Dexter found out about this after she tried to kill his sick, bedridden father Harry Morgan...and she became Dexter's first victim as a result.

Mary is Dexter's FIRST human kill, in a list passing over a hundred by Season Six. Since it was his very first human kill, it was rather messy...multiple stabs causing blood to pour out and more struggle than necessary in capturing his victim in her home.


While Harry Morgan was treated at a hospital, he realized that his nurse, Mary, was in fact an Angel of Death type serial killer who was killing him slowly by overdosing him with morphine as well as another unidentified substance. He gave Dexter Morgan the go-ahead to kill her in order to stop her from killing any more people. Dexter covered the interior of a room in her house with plastic and waited for her to arrive. When she did, however, he failed to sedate her with the syringe and had to take down using hand-to-hand combat. After being tied to a table, Mary was confronted by Dexter about her killings, using her souvenirs, her victims' obituaries, as evidence. She insisted that she helped them by putting her victims out of their misery, but Dexter threw her words right back at her by claiming he was taking her pain away. Dexter then gagged her again, repeatedly stabbed her to death and disposed of her remains in the Everglades swamp. Dexter's intervention prolonged Harry's life another year before he finally died.

It is unknown if Mary was ever identified as the Bay Harbor Butcher's first victim, (if the truth about her murders and death at the Butcher's hands ever came out). The police discovered the identities of all of the Butcher's victims when Dexter's blood slides were discovered, but since Dexter did not take a blood slide from her, it is unclear if the police discovered that she was the Butcher's first victim. If they ever did, however, her murder would have been blamed on James Doakes. There didn't seem to be any kind of major investigation into her disappearance, so the police presumably discovered her crimes after she disappeared.


Attempted Victims

  • Harry Morgan - Tried poisoning him with morphine but caught onto what she was doing and told her to stop. Later sent his son to kill her in preparation to kill more people like her.


  • Mary's last name was never revealed. In the original novels, her first name is also absent.
  • She was played by Denise Crosby, the actress who played Tasha Yar in ST:TNG.
  • On the Showtime "Kill Room", Mary's date of death is listed as 1991.
  • Mary was Dexter's first female kill shown in the series.
  • Denise Crosby also played a character with the same name in The Walking Dead