The Efrosians were a sentient, humanoid species, whose homeworld was a member of the United Federation of Planets by the late 23rd century. Efrosians served in Starfleet by 2286, and an Efrosian served as the Federation President as of 2293.
- See: Unnamed Efrosians
The name for this species never appeared in any script, dialogue, or production graphic. It was noted, however, in Paramount's initial publicity photos for Star Trek IV.
The name "Efrosian" was invented by Kirk Thatcher, an associate producer on Star Trek IV, in honor of unit production manager Mel Efros. (Information provided by Mel and Craig Efros) The design was based on a sketch by fantasy artist Thomas Blackshear. (Information provided by Kirk Thatcher) The name of this species comes from FASA's Star Trek IV Sourcebook Update. While strictly a non-canon source, it is the only widely recognized source for names of most of the Star Trek IV aliens. The name was never formally adopted by Paramount beyond the publicity photos which were printed in Cinefantastique #64, in fact, the Star Trek Encyclopedia, for example, goes out of its way to avoid using the name.
The Efrosian appliances were memorably uncomfortable for actor Kurtwood Smith, who played the Efrosian president. In a 1998 interview, he stated, "What I remember most about Star Trek VI was the outfit, the hair and mustache. I was so uncomfortable because I could not lie down. And those contacts! I wore blue contacts, so everything was blue all the time. That was very strange. The makeup took much longer than you would think from looking at the final product. I had a whole forehead piece and this wig. That stuff took four hours to apply and a couple more to take off. I was punchy during that shoot, because I couldn't take a nap or I would ruin the hair, and because of those blue contacts." (The Official Star Trek: Voyager Magazine issue 18, p. 33)
In the DVD audio commentary for Star Trek VI: The Undiscovered Country, Nicholas Meyer states that the Federation President is blind. This would seem to be inconsistent with the necessity of having visual aids for a briefing to the president by Colonel West, although the president is seen to use special glasses to read the briefing notes of Operation Retrieve. He has vivid blue irises and the other Efrosian, the USS Saratoga helmsman of Star Trek IV, has white-colored irises, leading to non-canon fan speculation that vision impairment is common among Efrosians. According to featured actress Lena Banks who portrayed the Federation president's assistant in Star Trek VI, the president was meant to be blind and her part was to guide him into the conference room. The scene was only part of the trailer for Star Trek VI and was cut out of the final film. (Information provided by Lena Banks)
According to the reference book Star Trek: Federation - The First 150 Years, the Efrosian homeworld was once a province of the Klingon Empire before joining the Federation; Ra-ghoratreii (the name given to the Efrosian president in non-canon works) thinks it significant that a man whose people had previously been subjugated by the Klingons is given the task of finally making peace with them.
In several novels published after 1986, the name for this species was Deltan, though differing from Lieutenant Ilia. The description of a long-haired male Deltan was introduced in Vonda N. McIntyre's novelization of Star Trek IV and was applied to the Federation President's race in J.M. Dillard's novelization of Star Trek VI.
More recent novels, such as In the Name of Honor and Articles of the Federation, use the name Efrosian. They are now said to come from a planet called Efros Delta (in the Star Trek: Titan novel Taking Wing).
According to the Titan novels, Efrosians do not have a written language, with their libraries resembling music archives. They also have no concept of monogamy and children are raised by their mothers alone.
According to the reference book Star Trek: Federation - The First 150 Years, Efrosians were once subjects of the Klingon Empire but managed to successfully rebel against the Klingons.
In 2003, Decipher issued a book for their role-playing game called Aliens in which the species name was given as "Atreonid". There has been unconfirmed speculation that this was at Paramount's request, although the name "Atreonid" has not appeared in any Star Trek productions.