El-Aurian

El-Aurians were a humanoid species of "listeners" originating from the El-Aurian system, who appeared to have an awareness superceding the normal flow of time and space. (TNG: "Yesterday's Enterprise"; DS9: "Rivals"; Star Trek: Generations)

El-Aurians traveled widely, visiting many parts of the galaxy. At least one El-Aurian visited Earth in 1893, before humanity had any official knowledge of alien species. (TNG: "Time's Arrow", Part I/Part II) In 2265 the Borg launched a major attack on this species, assimilating all but a handful. (TNG: "Q Who?", "Ensign Ro") The survivors scattered throughout the galaxy, finding homes among other races.

In 2293, the Federation transported a group of El-Aurian refugees 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 near the Sol system. The USS Enterprise-B saved some of the refugees, including Guinan and Dr. Tolian Soran.

El-Aurians prided themselves on being a race of listeners, and apparently had a limited form of empathic ability. Some used this to help others, acting as advisors or confidants. A few turned their talents to more dubious pursuits, becoming con men and tricksters, such as Martus Mazur, while Dr. Soran used his abilities to perpetrate a genocidal plan to re-enter the Nexus. (DS9: "Rivals", Star Trek: Generations)

Much of their seeming reticence stemmed from the El-Aurian racial character. They appeared to be natural lore-keepers, using their phenomenal lifespans and memories to collect the stories and life experiences of various sentient beings. They preserved this knowledge for their own kind, only occasionally sharing it with non-El-Aurians. A highly personable and empathic race, they were very willing to help other sentients work out their problems. El-Aurians were extraordinarily sensitive to the space-time continuum, possibly an offshoot of their prodigious memories and mental faculties. In 2366, Guinan perceived an alternate timeline which occurred because of a disruption in the starship Enterprise-C's history. (TNG: "Yesterday's Enterprise")
 * It was unclear if Guinan's special abilities and perceptions regarding time, and her ability to perceive Q, were completely the result of her lineage, or a side-effect of her Nexus experience.

Externally, El-Aurians were physically identical to humans in structure and even the range of racial phenotypes. The only significant physical difference lay in the aging process, as the extremely long El-Aurian lifespan covered many centuries.