Satan
Called Lucifer in heaven before the his disobedience, Satan is one of God's favorite angels until his pride gets in the way and he turns away from God. Satan brings many of heaven's angels with him, however, and reigns as king in hell. He continues an eternal battle with God and goodness for the souls of human beings. Satan, at first, is an angel with a single fault, pride, but throughout the story he becomes physically and morally more and more corrupt.
God
The Absolute, ruler of heaven, creator of earth and all of creation. God is all seeing, though he seems to pay less attention to things further away from his light. He is surrounded by angels who praise him and whom he loves but, when Satan falls and brings many of heaven's population with him, he decides to create a new creature, human, and to create for him a beautiful universe in the hopes that someday humans will join him in heaven. God has a sense of humor, and laughs at the follies of Satan and seems to be a firm and just ruler.
Son of God
God's begotten Son, later to become fully human in the form of Jesus Christ. God's Son will continually beat down Satan, first in the three day battle in heaven, then, as Jesus, when he sacrifices himself for the salvation of man. The Son of God is more sympathetic to the plight of mankind and often advocates on behalf of him in front of God.
Holy Spirit
Third of the God/Son Trinity. Although the Holy Spirit does not play a large part in the narrative (leading some critics to think that Milton did not even believe in the Trinity), he is continually referred to as Milton's inspirational "muse" in the writing of the epic. The Holy Spirit is, in fact, the creature through whom the Old and New Testament were written according to Christians, therefore he is the best vehicle from which Milton can draw the truth.
Sin
Daughter of Satan born when Satan first disobeyed God. Satan later rapes Sin and they have Death. The three form the unholy trinity in contrast to God, the Son, and the Holy Spirit. Sin is sent to hell with Satan and stands guard at hell's gates. She is a horrible looking thing, half serpent, half woman, with hellhounds circling her. She will invade earth and mankind after Satan causes Adam and Eve to fall.
Death
Spawn of Satan and Satan's daughter Sin. He is a dark, gigantic form who guards the gates of hell with Sin. He, too, will reign on earth after Satan causes the Fall. Death, however, will plague not only men and women, but all living creatures on earth down to the smallest plant. Death, as a terminal end, will be defeated when God sends his Son Jesus Christ to earth.
Adam
First created man, father of all mankind. Adam is created a just and ordered creature, living in joy, praising God. Lonely, Adam will ask for a companion and will thereafter feel deep and uncontrollable, though ordered, love for her, named Eve. This love will ultimately get Adam in trouble, as he decides to disobey God rather than leave her. Adam has free will and, by the end of the poem, also has the knowledge of good and evil.
Eve
First created woman, mother of all makind. Eve is rather a fickle and vain woman, easily flattered by Adam and Satan. Her weakness becomes her downfall, as her vanity drives her to disobey God. She loves Adam as well, though the implicaiton is that she loves herself much more.
Raphael
Gentle archangel sent to befriend and warn Adam of the dangers in the Garden. Raphael is traditionally seen as a friendly and sociable angel and, in fact, sits down to eat and gab with Adam for most of an afternoon. Raphael is a gentle guide and appears as a luminous, soft being.
Michael
General in God's army. In contrast to Raphael, Michael is a firm, military type of angel. He is more of an instructor and a punisher than he is a friend and a guide,. He and Gabriel are sent to battle Satan's forces in the heavenly war, and he is sent to evict Adam and Eve from Paradise.
Gabriel
Another archangel who is a general in God's army. He, too, was sent to lead God's forces into battle against Satan and it is he who, with a squadron of angel soldiers, finds Satan in the Garden of Eden the first time.
Abdiel
The only angel who stands up to Satan and his thousands of minions when Satan first suggests rebellion. He is praised as being more courageous than even those who fight in God's army because he stood up in the middle of evil and used words to battle it.
Beelzebub
Lord of the Flies, one of the Fallen Angels and Satan's second in command. Beelzebub is the name of one of the Syrian gods mentioned in the Hebrew Bible. He is the first with whom Satan confers when contemplating rebellion and he is the first Satan sees when they are in hell. Beelzebub relies totally on Satan for what he thinks and does. Later, Satan uses Beelzebub as a plant to get hell's council of fallen angels to do what he wants them to do.
Moloch
Another fallen angel, one of the generals of Satan's army. Moloch is an authoritarian military angel, who would rather fight and lose battles than be complacent and passive. Victory over God is less important to Moloch than revenge against him.
Belial
A complacent, passive fallen angel. Belial does not want to fight. He represents a part of all the fallen angels that secretly wishes God would take them all back.
Mammon
Another fallen angel. Mammon thinks that the fallen angels should try to build their own kingdom and make their life as bearable as possible in hell. He is the ultimate compromiser, and, though his compromise is illogical and will not work, the crowd loves him.
