Dr. Elizabeth Dehner was a female Human Starfleet officer who lived during the mid-23rd century. She served as a medical officer in the sciences division aboard the USS Enterprise in 2265 under the command of Captain James T. Kirk.
A medical study into Elizabeth Dehner's family history found that esper orientation and abilities were in both her paternal and maternal bloodlines; however, there was only one case where the tendency for ESP was traced back three generations.
She was born on stardate 1089.5, in the city of Delman, and was the daughter of Gerald Dehner. In the 2260s, she had earned a PhD in psychiatry and was the author of a medical thesis on esper-oriented beings.
Dehner had been aware of her esper rating (089), aperception quotient (20/100), Duke-Heidelburg quotient (256), and general knowledge quotient (654895-109) being better than average in all categories. Her abilities were evident in childhood, displayed in her superiority at guessing games, reading cards, and other activities. This was, in part, the basis for her vocational training as a psychiatrist. Participation in tests and studies of other related esper-oriented beings were the subject of a thesis published by her in association with the College of Medical Sciences of the Tri-Planetary Academy and was, in fact, the reason for her posting to the Aldebaron Colony.
Encounter with Galactic Barrier
She was aboard when the Enterprise went on an initial, fateful excursion beyond the galactic barrier, a journey that changed Gary Mitchell forever, causing him to develop psionic energy abilities. It changed Dehner, too, but this did not become apparent until much later, at Delta Vega. There, she began to develop abilities like those Mitchell had been displaying.
When Mitchell fled captivity, he took Dehner with him, into the hills of Delta Vega. Captain Kirk followed, determined to put an end to the threat posed by Gary Mitchell. Sensing Kirk's pursuit, Mitchell sent Dehner to intercept him; he hoped she would come to his opinion that mortals were highly insignificant. However, she retained enough of her Humanity to be appalled by Mitchell's actions and sacrificed her life to weaken Mitchell, an act that allowed Kirk to kill him.
Dehner was played by actress Sally Kellerman.
Since NBC executives had found the depiction of Vina as an Orion slave girl in "The Cage" (Star Trek's first pilot episode) too raunchy, the role of Elizabeth Dehner was deliberately much less sexual for the following pilot episode, "Where No Man Has Gone Before". Herbert F. Solow observed, "Not even the most conservative of conservatives could characterize the female guest-star role [of Dehner] [...] as being too erotic." (Inside Star Trek: The Real Story, pp. 61 & 66)
In the revised first draft script of "Where No Man Has Gone Before" (dated 27 May 1965), Elizabeth Dehner was described as "past her mid-twenties, rather tall and slim, with a face that could be beautiful if she cared to make it so. She doesn't. She has a normal quota of emotions, but they are carefully controlled and concealed behind a facade of sober intelligence." In the final revised draft of the script (dated 8 July 1965), the last sentence of that description was eliminated, and the character was scripted as having the middle initial "M", though this is not established in the episode's final version. Another facet that was scripted but isn't evident in the installment's final edit was that she was to initially appear horrified by Gary Mitchell showing her that, like him, she too had been transformed (with her eyes having turned metallic).
Director James Goldstone was involved in casting the part of Dr. Dehner. He remembered, "We read a number of other actresses for the role [....] I, along with Gene [Roddenberry] and whoever else, did cast Sally, but again, Sally went with [Mitchell actor] Gary [Lockwood] beautifully. There was a marvelous kind of physicality to her." (The Star Trek Interview Book, p. 106)
Unlike Gary Lockwood, Sally Kellerman had no problems with the silver contact lenses required for the role. (Inside Star Trek: The Real Story, p. 80) She did, however, have a problem with Dehner's uniform. Due to embarrassment over the fact that the tight costume was particularly close-fitting around her crotch area, Kellerman was given a "space clipboard" prop that she held close to her, covering up the problem, and was shot from the waist up, whenever possible. Also, because she at first speculated that women of the future would not wear brassieres, she initially suggested that Dehner not wear one, but James Goldstone persuaded the actress to change her mind. (Inside Star Trek: The Real Story, pp. 83-84) Kellerman ultimately thought she looked somewhat "pudgy" in the costume. She stated, "You know, I never had to wear anything like this before." (Starfleet Access for "Where No Man Has Gone Before", TOS Season 1 Blu-ray special features)
Denise Okuda cited Elizabeth Dehner as one of the many "strong" and "professional" women characters that "stood their ground" and were often conceived by Gene Roddenberry. (Starfleet Access for "Where No Man Has Gone Before", TOS Season 1 Blu-ray special features)
Dehner's biographical readout listed her age as 21, as of 2265 (stardate 1089.5), suggesting a birth year of 2244. It also listed her height as 5'2" and weight as 116. However, it was possible that the readout was a medical profile taken during her last examination, when she was 21, so she could very well be older during the events of "Where No Man Has Gone Before", as suggested by the script. Given that Kellerman stands 5'10" tall, Dehner's height listing is very much off the mark.
In the alternate reality-set IDW comic book Where No Man Has Gone Before, Part 1, Dehner was involved with Leonard McCoy at one point, a relationship that did not end well. She declined transfer to the USS Enterprise when she learned that he was onboard, and thus was not on the ship when they approached the galactic barrier.