Demons
In folklore, mythology, and religion, a demon or demoness
is a supernatural being that is generally described
as a malevolent spirit, but is also depicted as a
force that may be conjured and insecurely controlled.
The "good" demon is largely a literary device
(eg: Maxwell's demon).

As the Indo-Iranian Avestan and Vedic traditions
and also other branches of Indo-European mythologies
show, the notion of demon has been with those people
from very ancient times.

The PIE word *deivos, originally an adjective
meaning "celestial" remained its meaning in all
other branches of Indo-Europeans (Daeva, Deus, theo-)
but in a very early stage during the time of
Zarathustra the same word (Div) recieved
the notion of demon in the Iranian tradition.

The Greek conception of a daemon, δαίμων,
appears in the works of Plato and many other
ancient authors, without the evil connotations
apparent in the Septuagint translation of the
Hebrew Bible and in the Greek originals of
the New Testament. The medieval and neo-medieval
conception of a "demon" in Western civilization
(see the Medieval grimoire, the Ars Goetia)
derives from the ambient popular culture of Late
(Roman) Antiquity. The Hellenistic "Demon" eventually
came to include many Semitic and Near Eastern gods
as seen by Christianity.

Greco-Roman concepts of daemons that passed
into Christian culture are discussed in the entry daemon.

In some cultures demons are still feared in popular
superstition, largely due to their power to 'possess'
humans, and they are an important concept in many
modern religions and occultist traditions. In the
contemporary Western mystical tradition epitomized by
the work of Aleister Crowley, a demon, such as the
"Demon of the Abyss", Choronzon, is a useful metaphor
for certain inner psychological processes, one which is
nonetheless, in a sense, 'real' to those who experience
it as a separate being

The King and Queen of Demons
In some rabbinic sources, the demons were believed to be under
the dominion of a king or chief, either Asmodai
(Targ. to Eccl. i. 13; Pes. 110a; Yer. Shek. 49b)
or, in the older Haggadah, Samael ("the angel of death"),
who kills by his deadly poison, and is called "head of the
devils". Occasionally a demon is called "satan": "Stand not
in the way of an ox when coming from the pasture, for
Satan dances between his horns" (Pes. 112b; compare B.
Ḳ. 21a).

The queen of demons is Lilith, pictured with wings
and long flowing hair, and called the "mother of Ahriman"
(B. B. 73b; 'Er. 100b; Nid. 24b). "When Adam, doing penance
for his sin, separated from Eve for 130 years, he, by impure
desire, caused the earth to be filled with demons, or shedim,
lilin, and evil spirits" (Gen. R. xx.; 'Er. 18b.)

Though the belief in demons was greatly encouraged
and enlarged in Babylonia under the influence of
Parsee notions, demonology never became an essential
feature of Jewish theology. The reality of demons was
never questioned by the Talmudists and late rabbis;
most accepted their existence as a fact. Nor did most
of the medieval thinkers question their reality. Only
rationalists like Maimonides and Abraham ibn Ezra, clearly
denied their existence. Their point of view eventually became
the mainstream Jewish understanding.