An was a male Asgard scientist who was considered the Einstein of his species.
He was a geneticist who was working on a way to combat the slow cloning degradation that his race was suffering from. His work took him to the planet Earth long before they discovered the Stargate, where he was responsible for abducting the recently deceased in order to find out if Humanity was the key to their problem. He took with him his research assistant Loki in a scout ship, where a temporal accident resulted in An's death. (SG1: "Roswell")