El-Aurians were a humanoid species of "listeners" originating from the El-Aurian system. Data once speculated (going from appearances) that El-Aurians had an awareness that superseded the normal flow of time and space, since, as Jean-Luc Picard commented, there were many inexplicable things about them. (TNG: "Yesterday's Enterprise"; DS9: "Rivals"; Star Trek Generations)
The El-Aurians were a widely traveled people who spread themselves across many parts of the galaxy. It is known that at least one El-Aurian visited Earth in 1893, before Humans had any official knowledge of alien species. (TNG: "Time's Arrow", "Time's Arrow, Part II") Around 2265, the Borg launched a major attack on this species, wiping out all but a handful. (TNG: "Q Who", "Ensign Ro", "I Borg") The survivors scattered throughout the universe, finding homes amongst many species.
In 2293, a group of El-Aurian refugees were coming to Earth following their escape from the Borg. The two ships transporting the refugees, the SS Lakul and the SS Robert Fox, were caught in and destroyed by the Nexus energy ribbon near the Sol system. The USS Enterprise-B was able to rescue 47 of the refugees, including Guinan and Dr. Tolian Soran (at the cost of one James T. Kirk's life, or so it was thought). While Guinan would become the bartender aboard the USS Enterprise-D in 2365, Soran dedicated the following 78 years until his apparent death in 2371 to finding a way to return to the Nexus. Martus Mazur, another El-Aurian refugee, visited Deep Space 9 in 2370. (TNG: "Q Who", Star Trek Generations, DS9: "Rivals")
Externally, the El-Aurians were physically identical to Humans, in structure and even the range of racial phenotypes. The only significant physical difference between Humans and El-Aurians was in the aging process, as the extremely long El-Aurian lifespan covered many centuries. One El-Aurian male was known to be a father of an adult when he was around 200 years old in the 19th century, and to be around 700 years old as of the 24th century. (TNG: "Time's Arrow", "Rascals")
El-Aurians prided themselves on being a race of listeners, and appeared to have a form of limited empathic ability. Some used this to help others, acting as advisers or confidants. A few turned their talent to more dubious pursuits, becoming con men and tricksters, such as Martus Mazur, while Dr. Soran used his abilities to help bring his genocidal plan to re-enter the Nexus to fruition. (DS9: "Rivals"; Star Trek Generations)
Much of their seeming reticence came from the El-Aurian racial character. They appeared to be natural lore-keepers, and used their phenomenal lifespans and memories to collect the stories and life experiences of various sentient beings. They preserved this knowledge for their own kind, and only occasionally shared it with non-El-Aurians. They were a highly personable and empathetic race, and as such were very willing to help other sentients work out their problems. It is possible, as an offshoot of their prodigious memories and mental facilities, that El-Aurians were extraordinarily sensitive to the space-time continuum itself. In 2366, Guinan was able to perceive an alternate timeline that occurred because of a disruption in the starship USS Enterprise-C's history. (TNG: "Yesterday's Enterprise")
If Guinan's presence on Earth in 1893 is any indication, El-Aurians often travel across the galaxy, seeking out interesting stories to listen to. Guinan herself traveled to Earth before it developed spaceflight, and ultimately sought out the company of local luminaries and literary greats such as Mark Twain. (TNG: "Time's Arrow", "Time's Arrow, Part II")
- See El-Aurians
- "The Child" (Season Two)
- "The Outrageous Okona"
- "The Measure Of A Man"
- "The Dauphin"
- "Q Who"
- "Evolution" (Season Three)
- "Booby Trap"
- "Deja Q"
- "Yesterday's Enterprise"
- "The Offspring"
- "Hollow Pursuits"
- "The Best of Both Worlds"
- "The Best of Both Worlds, Part II" (Season Four)
- "The Loss"
- "Galaxy's Child"
- "Night Terrors"
- "In Theory"
- "Redemption II" (Season Five)
- "Ensign Ro"
- "Imaginary Friend"
- "I Borg"
- "Time's Arrow"
- "Time's Arrow, Part II" (Season Six)
Background information Edit
According to the reference book Star Trek: The Next Generation Companion (3rd ed., p. 319), the El-Aurians were named after an "angel of flame" from ancient Hebrew lore. Though many people think the name of the species was first established in Star Trek Generations, it actually originated in DS9: "Rivals". However, the name was likely taken from early drafts of Generations, which were definitely in circulation around the Star Trek office at Paramount by the time "Rivals" entered production. (Star Trek: Deep Space Nine Companion, p. 109)
For Star Trek Generations, Costume Designer Robert Blackman was assigned the task of designing individual costumes for thirty El-Aurians. This challenge was welcomed by Blackman, as working on Star Trek: The Next Generation had involved him encountering tight budgets and schedules that usually didn't allow for more than seven alien individuals to be shown per episode. (Star Trek: The Next Generation - The Continuing Mission, p. 231) In Generations, however, El-Aurians other than Guinan and Tolian Soran are shown in only one scene. The master version of this scene, used in the first edit of the film, spotlighted all of these individuals. 
Descriptive text about Guinan in the internal reference work Star Trek: The Next Generation Writer's/Directors' Guide (special edition 1992–1993) states that several El-Aurians met Jean-Luc Picard while he was serving as a lieutenant on board the USS Stargazer and that they fascinated him at that point. The description also explains that the fact they were often described as a group of listeners was because something about the species "encourages others to be honest when they speak." (Star Trek: The Next Generation 365, p. 012)