Dr. Helen Noel was a female Human enlisted crewmember in the 23rd century. She served in the sciences division aboard the USS Enterprise in 2265 to 2266 under the command of Captain James T. Kirk, during its historic five-year mission. She was a psychiatrist with a background in rehabilitative therapy. (TOS: "Dagger of the Mind")
In 2265, Noel was assigned to the medical department aboard the Enterprise. That same year, she attended the science lab Christmas party, where Noel met Kirk and danced with him. At the same event, she heard him talk about the stars, and he addressed her by her first name.
In 2266, after Simon Van Gelder escaped from Tantalus Colony, Dr. McCoy, the department head of the ship's medical department, casually recommended Noel to Kirk, as a technical aide when the captain planned to investigate Van Gelder's treatment at the penal colony. She subsequently accompanied Kirk on a visit to the colony, with the aim of speaking to Dr. Tristan Adams regarding the accident which had purportedly caused Van Gelder to become insane, among other things.
Noel was able to advise Kirk about the neural neutralizer. While not familiar with the specific equipment in use on Tantalus V, she was familiar with the concept, and assured Kirk that Adams had not created a "chamber of horrors" in the neural neutralizer – an assumption later revealed to be horribly wrong.
After hours, Kirk enlisted Noel's aid in a hands-on demonstration of the neural neutralizer. Convinced she would be able to evaluate the effects and determine whether the device was injuring him, he acted as the subject, while she operated the equipment. They had discovered the device was far more effective than initially suggested when Adams and Eli overpowered her and began to employ the device to mentally condition Kirk. Included in this conditioning were powerful romantic feelings towards Noel, based on their chance encounter at the Christmas party.
When Kirk awoke after his treatment, he fought off his feelings for Noel long enough to dispatch her through a series of air conditioning ducts to the colony's power supply. There, she managed to shut down the power to the colony, enabling Kirk to escape the treatment room, and the Enterprise's first officer, Spock, to beam down with a landing party and secure the colony. (TOS: "Dagger of the Mind")
Helen Noel was portrayed by Marianna Hill.
This character was created as a replacement for pre-established Yeoman Janice Rand, who originally would have accompanied Kirk to Tantalus V. The new role was devised while the episode's script was being written. (The Star Trek Compendium, 4th ed., p. 42)
In the final draft script of "Dagger of the Mind", Dr. Noel was described thus; "She is young, exceedingly, even uncomfortably, lovely [....] Her face is intelligent but the graceful, young and very female body is scarcely what Kirk had in mind when McCoy casually mentioned scientific assistance."
The TOS novel The Weight of Worlds mentions that she transferred to the USS Reliant sometime after the events of "Dagger of the Mind". Kirk considers declining to appear at the yearly Enterprise holiday party upon recalling his awkward interactions with Noel after their rendezvous at that year's party, and is relieved that she has since transferred off the Enterprise.