Wraith

The Wraith are the dominant species in the Pegasus galaxy. They are biologically immortal hive-based humanoids who feed on the "life-force" of humans, causing them to "lose years" in a way similar to aging. The Wraith drove the Ancients out of Pegasus 10,000 years ago, and now maintain the human worlds of Pegasus as sources of food. Some people believe that the ancients are responsible to the creation of this race.