Term identifying Athosians who were spared from death by the Wraith, even after they were culled, and possessed extra-sensory abilities after the fact. The Athosian Charin was the only surviving member of her race who remembered stories of this breed of people. She eventually passed on the knowledge to Teyla Emmagan.
According to Athosian history there were a select few individuals who were returned to a specific Athosian colony. Many believed it was a gift from the Ancients that their loved ones returned, and many others feared them, as the individuals began to behave strangely. The taken spoke of hearing voices. Some became violent and even murderous. Eventually the villagers of this world turned on the taken. In the massacre, all but a few were killed.
The few taken who survived were ostracized from the community, surviving among other Athosians and passing the "gift" to their offspring. Today very few Athosians have the abilities of the taken.
As was discovered by Teyla and John Sheppard's unit, a Wraith was studying ways to enhance the feeding process so that humans would essentially become "tastier." Instead, he realized that he was enhancing his enemy with Wraith abilities, and eventually gave up.
The Gift - Teyla learns of the taken from Charin, an Athosian elder who was sworn by Tagan to never tell his daughter of the truth.