Celestial

The term 'celestial' refers to any species sent to walk the planet by either God or Satan. This includes: Angels, Demons, Imps, Nephilims, and Seraphims. Whether or not Imps fall under the 'celestial' umbrella has been a source of debate; though, because they are a cross between two definitively celestial beings, they are counted legally.

Origin
Celestial beings appeared on the Earth during the First Apocalypse. Due to unknown circumstances, pieces of Heaven began to fall to the Earth, bringing many Angels down with it and wiping out many of the humans in the process. Enraged and jealous, Satan then sent up many of his Hellions, and so the Demons rose to the surface. Because of how quickly they began to clash, Angels and Demons segregated themselves to different continents, creating what we now know as Alurra and Irroz, respectively.

Because of all of the chaos in the world, God then sent Nephilims to Earth, but segregated them to the Valley of Rephaim, hoping that their mere magical presence alone would calm the clashing sides. What effect this had, however, is not recorded. After many centuries of peaceful life, the Nephilims eventually evoked the wrath of the Holy Crusader, causing the Second Apocalypse and the creation of the Seraphim.

Imps are the children of one Angelic parent and one Demonic parent. This is illegal in most countries, and the date of first Imp birth is unknown. Because they are a cross between two Celestial beings, they are legally considered Celestial, but there have been many debates about this, critics calling Imps "impure" and "abominations."