In the science fiction television series Stargate Atlantis, the Wraith are the original antagonistic alien species, first introduced in the pilot episode "Rising". In the early seasons of the show they dominated the Pegasus Galaxy, the show's setting, and were an almost unstoppable and fatal threat. In Season 1, it was the prime objective of the characters to find a way to save themselves from a siege by the Wraith, similar to how the characters of Stargate SG-1 (Atlantis' sister-show) were originally focused solely on protecting Earth from attack by the Goa'uld. Although still immensely powerful in number, various other threats including the Ori have also arisen which have taken attention away from the war against the Wraith.
The Wraith are depicted as a hive-based species that grew to their level of power through parasitism (much like SG-1's Goa'uld), and have traits very similar to those of vampires. Wraith "feed" by "sucking" the life-force from a human being and are ageless. They have likely evolved from a combination of human and insectoid genetic recombination, which suggests the reason for why their abilities are as such.