Upon reading the Apocrypha of the Bible and the early books of the canonical Bible, you quickly start to pick up on a story about angels not often mentioned in other texts. The Watchers were the two hundred angelic beings, part of an order of archangels that were charged with guarding the earth. In some myths, the Watchers were the ones who guided and assisted our spiritual (and perhaps, literal) evolution. In others, they were rebellious and arrogant to a fault, eventually leading them to follow Lucifer in a desertion of epic proportions.
In most stories, the Watchers number two hundred, with twenty being the leaders responsible for the rest. Some early manuscripts of the second book of Enoch put their number at 2 million. The location of this fallen host is said to be the fifth heaven, according to Enoch 2, along with Satan.
The Watchers taught humanity much hidden knowledge that was to be revealed to us in a gradual manner and not given all at once as it was. The demons taught our race everything from signs to phases of the moon to cosmetics and warfare. One of the higher-ranking Watchers, Kokabiel, was said to have over 300,000 spirits at his command and taught humans astrology, which was forbidden as one of the secrets of heaven.
In the book of Genesis, they are referred to as Sons of God, supernatural beings that lusted after the daughters of men. The angels left their posts and took the women as they pleased, thus angering God. The story goes that the rebellious angels, led by Samael or in some texts, Azazel (a common reference, though the devil goes by many names), were thrown to the earth and chained in the valleys of the earth until judgement.
In Chapter 18 of the second book of Enoch, the children of these unions, the Nephilim, or the Grigori as it is translated there, have human likeness but are brutal giants that ravage humanity. God soon passes his judgement on the offspring of these unions and sends the deluge to cleanse the earth from them once and for all. This is the beginning of giant lore.
It is unclear how long the savage children of the Watchers were allowed the fulfilment of their bloodlust, only that they are said to have been destroyed in the flood. However, giants are mentioned again in the Bible later in the book of Numbers when Moses sends two spies to scope out Canaan, saying that they were as grasshoppers to the people that were living there.
The crossing of archangels and humans apparently bred a race of bloodthirsty giants that loved nothing more than terrorizing and feeding upon humans. Giant vampires. Yikes.
In the Book of Giants, God sends Enoch to warn the Nephilim of his impending judgement for not only their rebellion, but for defiling everything they could get their hands on including each other, eating one another’s flesh and drinking the blood. Rather than turn from their debauchery, many of the Nephilim chose to continue on in defiance of God’s orders and the rest is history.
There are some who interpret the name “Sons of God” and the phrase “heroes of old” in the book of Genesis in reference to the Watchers to allude to aliens or extraterrestrials. While Ezekiel’s vision in the book of the same name in the Bible does describe some strange machinations like chariots of fire with eyes and wheels with eyes, most biblical scholars concur that these visions were of an order of angels charged with proclaiming the holiness of God, the Thrones. These angels appear as wheels and are an entirely different order of angels than the Watchers.
Although, I think if demons exist, they would be entirely capable of deceiving us into believing just about anything.