From Cassius Comics

One of the most powerful alien empires in the known universe, the Shi'Ar have been on relatively good terms with the planet Earth for a number of years, thanks in no small part to the history between Earth's Professor X and the Shi'Ar Majestrix, Lilandra Neramani. The two were actually wed for a number of years, but their marriage was recently officially terminated.

Despite their current good relationship, the Shi'Ar has targeted Earth as an enemy on at least two occasions, first when they were led by the evil D'Ken who targeted the planet in his quest to control the M'Krann Crystal, and again, more recently, when they joined in a coalition of planetary forces and designated Earth as an interstellar penal colony. The Shi'Ar eventually just severed all ties with the planet when the The Phoenix Force returned to inhabit Jean Grey, but with her death, the Shi'Ar's current attitude towards Earth is unclear.

The Shi'Ar have been through at least one massive war in the past generation, specifically a war with the Kree. Their conflict was resolved through a most unexpected turn of events, as the Kree's leader Supremor detonated a bomb that killed billions of Kree, effectively destroying any thoughts they had of external combat.

The Shi'Ar people are said by some to vaguely resemble birds.