Deltan
The Deltans were a humanoid species originating from the planet Delta IV. They were members of the United Federation of Planets.
Physiology
Deltans were identified by their fair skin and bald scalps. They had pain-relieving abilities that manifested during tactile contact. This ability did not, however, heal injuries. Deltans believed Humans to be a sexually immature species. Because of their high sexuality, Deltans had to swear an oath of celibacy upon entering service in Starfleet, as a promise not to take advantage of any fellow crewmember. (Star Trek: The Motion Picture)
History
In 2141, the ECS Horizon encountered a group of Deltans. Travis Mayweather, who was fifteen at the time, later described them as very attractive and very open. His method of dealing with the feelings they engendered in him was exhaustive workouts in the gym, a method he returned to (and recommended to Lt. Malcolm Reed) while three Orion slave girls were "guests" aboard Enterprise. (ENT: "Bound")
One Deltan, Starfleet Lieutenant Ilia, made direct contact with the V'Ger entity when it approached Earth in 2272, whereupon she was listed as missing in action. (Star Trek: The Motion Picture) Another Deltan served as an officer aboard the USS Excelsior in 2285. (Star Trek III: The Search for Spock) A male Deltan ambassador served on the Federation Council in the same year. (Star Trek IV: The Voyage Home)
Apocrypha
The Deltans' strong sexual presence, even without physical contact, was explained by pheromones and sub-conscious telepathy in Gene Roddenberry's novelization. When Lt. Ilia first appeared in the novelization, James T. Kirk reflected that he seemed to instinctively perceive her as naked, despite the fact she was in uniform, and realized this illusion was due to her baldness. References to some of the Deltans' sexual tendencies and oaths were removed from some versions of the filmed appearance.
In the script of Star Trek II: The Wrath of Khan, stage directions indicated that the Project Genesis scientist, Jedda, was Deltan. The novelization of Star Trek II expanded on this, adding a female Deltan partner. It was also said that sexual activity between a Deltan and a non-Deltan means risking insanity for the non-Deltan.
