Television: Stargate: SG-1

Many people are undoubtly aware of the Stargate series. The basic premises is that long ago a race of beings known as the "Ancients" built devices known as Stargates that connected the galaxy through locations on various planets. A group of aliens known as the Goa'uld in the past used the Stargate to occupy earth and built the great Egyptian Empire. We also find that thousands of humans were taken and used to seed planets as a slave race.

Hundreds of years later in the modern world, the US government has been using the discovered Stargate and exploring the different worlds. They have re-engaged the Goa'uld and manage to fight them off. Later in the series, they come in contact with a race known as the Asgardians. Ironically they are a type of tan "grey" that have been observing the earth for hundreds of years. They liberated on Goa'uld seed planet, and were hoping that one day the humans there would evolve and could be contacted peacefully. However, the SG-1 team stumbled upon them and made first contact. Since then the Asgardian have become interested in Earth.

 One such Asgardian, named Thor, has been the delegate to the humans of earth. We later fine that a rogue Asgardian named, Loki has been conducting genetic experiments with earthlings. As the series progresses we see the SG1 and the Asgard co-operate on many levels.
Sadly we find out that they suffer from genetic degradation from the overuse of cloning. They have reached a point in which they can no longer clone themselves. Sadly as a race they seem to have been wide up do to this degradation.

However, in a spin off of the series "Stargate: Atlantis" we find another colony living in the Pegasus galaxy. Unlike like the Asgardians, they are more warlike as they had to deal with the Wraith in their sector. They do not seem to suffer from the degradation yet.