Rabbinical demonology, which was heavily influenced by the ancient Chaldean (Babylonian) religious system, states that there are three main classes of demons. They are the shedim, the mazzikim (harmers) and the ruhin (evil spirits). Besides these, spirits were classified based on the time of day in which they were active (morning, midday, evening and night spirits).
The king or ruler of all the demons is called Adhmodai, or, in still older traditions, Samael (Satan). He is considered an enemy of man but not an opponent of God or what is good. According to tradition, his "fall" took place not before the creation of man (which is what the Bible teaches - Ezekiel 28:14 - 16, Isaiah 14:12 - 14, Luke 10:18) but after it.
Lilith is considered the queen of the demons. Her name is taken from the Hebrew word liyliyth (Strong's Concordance #H3917) found only in Isaiah 34:14. The KJV Bible translates the word as "the screech owl." Jewish tradition, however, holds that the word means "night specter" (night demon or night monster) and that it refers to a well-dressed woman who, at night, can carry off children or those who sleep alone in order to harm them.
Additionally, evil spirits, according to rabbinic teaching, can be either male or female (Scripture teaches that all spirits, including God, are sexless). Instead of their number being fixed it is taught they were allowed to greatly multiply through male spirits procreating with Eve and female spirits reproducing themselves through Adam before the birth of Seth (Genesis 5:3).
Concerning the vast number of demons taught by the Rabbis, the Catholic Encyclopedia states the following.
"One characteristic of Jewish demonology was the amazing multitude of the demons. According to all accounts every man has thousands of them at his side. The air is full of them, and, since they were the causes of various diseases, it was well that men should keep some guard on their mouths lest, swallowing a demon, they might be afflicted with some deadly disease" (1913 Catholic Encyclopedia article on Demonology)
Demons in the Bible
Such idolatry was clearly condemned in the Bible. Leviticus 17:7 states, "And they shall no more offer their sacrifices unto devils (saiyr), after whom they have gone a whoring. This shall be a statute for ever unto them throughout their generations" (KJV).
The shedim (or shed), Strong's #H7700, literally means "devil" or, according to the 1906 Jewish Encyclopedia, a "storm demon." They, too, were worshipped by the Israelites, as Scripture states "They sacrificed unto devils (shedim), not to God; to gods whom they knew not, to new gods that came newly up, whom your fathers feared not" (Deuteronomy 32:17, KJV, see also Psalm 106:37).
Demons can also be referenced as spirits that are evil (Judges 9:23), lying (1Kings 22:22 - 23), perverse (Isaiah 19:14), unclean (Zechariah 13:2) or familiar (Leviticus 20:6).
Categories of Restraint
Two broad categories of demons exist based on the level of freedom they have to carry out their evil desires. The first are those who have been given a measured amount of freedom to deceive, possess and bring trials to humans (Ephesians 6:11 - 12). The devil and at least some fallen angels are in this first category.
The second broad category of evil angels is those who are being restrained (imprisoned) by the Eternal. Some of these wicked or unclean spirits WILL be let loose in the very near future. God will release them, during the prophetic period known as the Day of the Lord, in order to punish humans for refusing to repent.
13. And the sixth angel sounded his trumpet; and I heard a voice from the four horns of the golden altar that is before God; 14. And it said to the sixth angel, who had the trumpet, "Loose the four angels who are bound in the great river Euphrates." 15. Then the four angels, who had been prepared for the hour and day and month and year, were loosed, so that they might kill a third of men (Revelation 9:13 - 15, see also verses 1 to 4).
Still others who are being restrained will not be taken out of their spiritual prison until the time of their ultimate judgment.
4. For if God did not spare the angels who sinned, but, having cast them into Tartarus (a place of restraint referenced only here), delivered them into chains of darkness to be kept for the judgment . . . (2Peter 2:4, HBFV)
6. And the angels who did not keep their own original domain, but deserted their habitation (and became demons), He is holding in eternal bonds under darkness unto the judgment of the great day (Jude 1:6, HBFV).