The name of Azrael was chosen by Denis O'Neil by flipping through a mythology book. This angelic name has long applied a whole body of "weight" to this comic character, supplying it with a history of associations not inherent to many characters.

Azrael Lore
Azrael, in Islamic theology, Azrael is the Angel of Death. He is "forever writing in a large book and forever erasing what he writes: what he writes is the birth of man, what he erases is the name of the man at death." The Angel of Death figure appears in many religions but under different names. Judeo-Christian names for the angel of death range from Michael, Gabriel, Sammael, to Sariel. Rabbinical lore lists 14 angels of death: Yetzerhara, Adriel, Yehudiam, Abaddon, Sammael, Azrael, Metatron, Gabriel, Mashhit, Hemah, Malach ha-Mavet, Kafziel, Kesef, and Leviathan.

The Talmud (Jewish Holy Book) has references that equate Angel of Death was equated with Satan, thus supplying the inference that this angel is evil rather than good. As a side note, Azrael in Hebrew supposedly (according to some sources) means "assistant or helper to the gods." (and thus angel!)

In Islam, Azrael (also Izra'il) stands as one of the four Archangels of Islam (The others are Djibril, Mikhail, and Israfil.) hell and paradise.

"Supposedly Azrael brought God a handful of earth from which to create Adam and therefore earned his title as the Angel of Death. Izra'il keeps a roll of humanity, on which the names of the damned are circle in black and the names of the blessed, in light. When a person's day of death approaches, a leaf with the person's name on it falls from the tree beneath God's throne. After forty days have passed, Izra'il must sever the individual's soul from his or her body. Azrael will be the last to die, but will do so at the second trump of the Archangel. He is the angel who accompanies your soul to Heaven."

Astrological References to Azrael
Azrael has governance over death and the life after the death. Azrael is also associated Scorpio as is Sammael. The astrological planets are Mars and Pluto. The element of Azrael is water (an interesting contrast to the fire imagery within Azrael the comic). The stones associated with the astrology of Scorpio are the ruby, garnet, topaz, and bloodstone. The plants associated are basil and chrysanthemum as well as heather. Colors, naturally, are dark red, brown, black, grey. The day of the week associated is Tuesday.

General Note on Angels
Angels are said to be the holy hands of God...his physical messengers, bearers, etc. They are celestial beings. Most Christian literature groups them into a heirarchy. The names of the nine orders of angels (from New Testament, Eph. 1:21 and Col. 1:16), the orders are:

1. Seraphim, Cherubim, and Thrones in the first circle of the heavenly heirarchy. They are closest to God and contemplate his goodness.
   
2. Dominions, Virtues, and Powers in the second and preside over the ordering of the universe.
   
3. Principalities, Archangels, and Angels in the third level and have dominion over man.
   

Basically, there are 7 holy angels are Michael, Gabriel, Raphael, Uriel, Chamuel, Jophiel, and Zadkiel. Christian Legends speak of 4 archangels: Michael, the warrior; Raphael, the healer; Gabriel, the herald; Uriel, the bringer of light. The Koran has 4: Azrael the angel of death, Gabriel the angel of revelations, Michael the faith keeper, and Israfel, the one who sounds the trumpet at the resurrection.

Angels were considered to be the level above man...a being closer to God, a servant and worshipper of God. However, one angel (as depicted in Milton's work) reveals that although they are higher up, angels are not perfect! Lucifer, the Mornning Star, the Light-bringer, the Left Hand of God, refused God for he did not care for man. Thus he caused a war in heaven. The war divided the angels, and many fell with Lucifier to Hell - the fallen angels who became his demons when he gained the role of Satan.