The Centaurians are a blue-skinned space faring race. Centaurians are one of the many races encountered by the Asgardians in the Nine Realms and the worlds beyond Yggdrasil.
After encountering the corpse marked as G.H. inside the facility known as The Guest House, Phil Coulson asked Lady Sif if she had met any blue alien species. When Sif replied, she listed, among others, Centaurians.
She added that the Centaurians had never been on Earth, without knowing that one of the Centaurians, Yondu Udonta, came to Earth in 1988 to kidnap a young Peter Quill.
- Yondu Udonta