- "I shall ascend above the heights of the clouds; I shall be like the Most High."
- —Satan in Isaiah 14:14.
- "All these and more shall be yours if thou bow down and worship me."
- —Satan to Jesus.
- "Better to reign in Hell than serve in Heaven."
Satan is regarded by the Christianity and various religious groups as the supreme overlord of the hierarchy of Hell or alternatively as a living embodiment of evil whose power is second only to that of God and faith - although Satan is a Christian concept almost all orthodox religions have an evil godlike (or semi-godlike) figure that can be said to be connected to Satan in their mannerism and purpose. In jewish religion he is also known bad but he is one of God's angels. Satan serves as the main antagonist for the jews & christians.
To some Satan is "almost" all-powerful while others limit his power to only corrupting or deceving mankind - some religions do not regard Satan as pure evil and instead believe he is granted the ability to corrupt humanity in order to test faith - though in the popular mind Satan will always embodies the raw and evil demonic possession. 
Origins of Satan
Satan was originally called Lucifer, the Morning Star, which means light-bearer. Before his rebellion and eventual defeat, Lucifer is considered to have been either the first or the second most powerful Archangel. Eventually, he grew prideful and jealous of God's power and attempted to overthrow him, gathering up legions of followers and revolting against God. He was defeated by Michael and cast into Hell as punishment. It is said that on the Day Of Judgment Satan shall rise to power again and lead another war against Heaven, this time he and his followers will be cast down by God himself and sent to a lake of burning fire (Hell) as an eternal punishment for their many sins.
In Islamic belief, Satan is referred to as Iblis and did not rebel against God out of a jealousy of the Creator's power but rather out of contempt for mankind - who God created and had his other creations bow down to: Iblis refused to bow to mankind (some say he knelt before God only) and was thus banished from Jannah ("Paradise") and given only the power to corrupt humans until the day God would return to pass judgment on the world. In the Old Testament, he is simply an angel referred to as ha-Satan, or the Adversary. It is important to note that he was viewed as the monster of man, not God. He was one of God's closest angelic advisors. The Satan's job was to tempt man away from God's law. This was intended as a means of testing man's righteousness. another thing is that Satan did not rule Hell in the old testament.
Description of Satan
A description of Satan is found in the Old Testament. Ezekiel 28:12-19
"...You were the perfection of wisdom and beauty. You were in Eden, the garden of God. Your clothing was adorned with every precious stone – red carnelian, chrysolite, white moonstone, beryl, onyx, jasper, sapphire, turquoise, and emerald – all beautifully crafted for you and set in the finest gold. They were given to you on the day you were created. I ordained and anointed you as the mighty angelic guardian. You had access to the holy mountain of God and walked among the stones of fire. You were blameless in all you did from the day you were created until the day evil was found in you. Your great wealth filled you with violence, and you sinned. So I banished you from the mountain of God. I expelled you, O mighty guardian, from your place among the stones of fire. Your heart was filled with pride because of all your beauty. You corrupted your wisdom for the sake of your splendor. So I threw you to the earth and exposed you to the curious gaze of kings. You defiled your sanctuaries with your many sins and your dishonest trade. So I brought fire from within you, and it consumed you. I let it burn you to ashes on the ground in the sight of all who were watching. All who knew you are appalled at your fate. You have come to a terrible end, and you are no more."
In popular culture Satan is depicted as a red-skinned humanoid with the legs of a goat, similar in many ways to the Roman god Pan, he varies from having bat-like wings or none at all and tends to have a long tail with a forked end - his weapon of choice tends to be a pitchfork and he is always seen tending to the fires of hell or tempting some poor soul: an adept shape-shifter Satan is said to take on any form he pleases in order to tempt people but the satyr form (known as a Devil) remains one of his most famous personas.
Satan is also frequently confused with Baphomet, a goat-headed demon strongly associated with black magic and due to this the two beings often merge - this is also the case of many of Satan's alter-egos, such as Beelzebub (lord the flies) or Baal - many of Satan's alter-egos are based on ancient fertility gods or pagan deities that the early church viewed as evil and thus added into an infernal hierarchy of demons with Satan as their lord and master: over the centuries however demonology became less popular and the infernal hierarchy concept faded away (though some still believe in it).
Satan is the embodiment of pure evil. In the story of Adam and Eve, Satan is represented as a serpent. He tricks Eve into eating the forbidden fruit through deception and manipulation. It is said that sin is caused by temptation, which, in turn is caused by Satan, thus, making Satan was responsible for mankind's first sin.
Satan also embodies the darker parts of humanity that most civilized people frown upon: things such as violence, lust and a lack of faith - a reminder of the more animalistic (or savage) origins that humans may of had and the fear that without proper guidelines (such as the Biblical Commandments or modern law) we would return to such savage behavior (a good example of this thought is seen in the story The Lord Of The Flies).
Role in Heaven
Before his fall, Satan held the position of Accuser, which was a position much like a prosecutor in modern human courts - he was also seen as God's most beloved angels in many texts yet became his most powerful and recurring opponent following his Fall.
Although rarer than the classical "fallen angel" theory there has been a school of thought (largely seen as heretical by orthodox scholars) that the Old Testament "God" - with his frequent displays of anger, strict enforcement of rules and what some may argue as petty vengence - was indeed "Satan" while figures such as Jesus represented a "demiurge" of sorts that sought to free humanity from a cycle of sin created by a malicious or uncaring higher-power.
This school of thought is popular with some Theistic Satanists, who see Lucifer as a champion of freewill who fought against a tyrannical God - of course the idea of a malevolent God is not accepted by most within mainstream religion and in the past people were oppressed for teaching such doctrines.
Yet despite this the idea of God (usually the Old Testament version) as Satan still exists and is held as fact by some, especially those who are embittered towards the Church or disagree with the events of the Bible, which may be viewed as violent and intolerant to those who do not share its views or morals.
The idea of God portraying as Satan was later used to create the the main villains of the His Dark Materials trilogy, The Authority, the first angel who claimed to be God and created Judeo-Christian-Islamic religions but was only a fraud, and his Regent Metatron, an evil man-turned angel who ruled Heaven and was the one responsible for the Magisterium's (Church) oppression and corruption and hatred towards free-will.
Throughout history, there have been many people who worshiped Satan. Long ago, a segment of the Catholic Church, called the Inquisition, searched for Witches, who they believed worshiped Satan. During this time, many people were falsely accused of witchcraft, leading them to be brutally tortured by the Inquisition. Nowadays, Satan worshipers are called Satanists.
(It is worth noting however that technically Satanism is not the actual worship of Satan - unless it is what is referred to as Theological Satanism, societies such as the Church of Satan are not practitioners of Theological Satanism and instead embrace a more humanistic (albeit selfish) philosophy that doesn't worship any external deity or demon, rather seeing individuals as their own gods - Theological Satanism is rare but does exist, though it is often confused with many other philosophies known as the Left-Hand Path).
Satan, like the concept of evil he embodies, takes many forms and has also taken many names: most of Satan's alter-egos can be traced either to ancient fertility-gods that were demonised by the early church or high-ranking demons that have gradually become intertwined with the legend of Satan and become more renown as a part of Satan himself, some of his more well-known names are:
The Devil, Lucifer, Beelzebub, Prince of Darkness, Lord of Illusion, Prince of Lies, Father of Lies, The Great Deceiver, The Serpent, Nicholas Scratch, Mr. Stratch, The Beast AKA (Dean Gladue), Pazuzu, Moloch and Ba'al.
Satan also holds titles that explain what he is such as:
- Morning Star
- Lord of Evil
- Prince of Darkness
- Father of Lies
- The Serpent
In Dante Alighieri's epic poem, The Inferno, Satan is trapped in Cocytus, the ninth and final circle of Hell; the circle reserved for the treacherous and traitorous. He is depicted with three heads, in a mockery of the Holy Trinity (God, Jesus, and the Holy Spirit), and each head is chewing on a dead soul. Within Satan's left and right mouths feet-first are Brutus and Cassius, the murderers of Julius Caesar. In the middle mouth head-first is Judas Iscariot, betrayer of Jesus Christ. He suffers the worst torment of all, having his head chewed and back raked by Satan's claws for all eternity.
Satan himself is trapped waist-deep in a sheet of ice. His wings beat in an eternal struggle to escape his frigid prison, yet the winds that his wings create only ensures that he is trapped further along with every other soul in Cocytus. Vergil and Dante escape Cocytus by climbing down Satan's fur through the center of the world, and reemerging at the mount of Purgatory.
In Popular Culture
Satan is the chief antagonist of innumerable television shows, movies, video games and novels - though he is often renamed and his religious origins toned down out of the great controversy his very name can inspire in certain groups: however some people have deliberately played on Satan's ability to stir up controversy and added him into their work for that purpose: many Metal groups use Satanic imagery as a way of sparking controversy and seeming rebellious, though very few of them are truly Satanists and only play the part for their audiences.
Some notable films, novels and other media that has Satan as the chief antagonist are:
- The Devil's Advocate (as a powerful law firm owner named John Milton played by Al Pacino)
- Reaper (as The Devil)
- John Carpenter's Prince of Darkness (as a primordeal green liquid with the power to possess people while seeking to release his father)
- The Exorcist (technically Pazuzu is the antagonist but Satan was referenced many times)
- The Divine Comedy (not an antagonist perse but is described in detail along with his kingdom, Hell)
- Rosemary's Baby (only mentioned as the father of the baby of the frightened Rosemary)
- The Omen (technically the Antichrist. but the two are similar beings)
- Bedazzled (played by Peter Cook in the 1967 and Elizabeth Hurley in 2000)
- Futurama (the Robot Devil or Beelzebot from the popular animated series Futurama)
- Needful Things (as a mysterious proprietor named Leland Gaunt portrayed by Max von Sydow)
- Terror Toons (as the creator of Doctor Carnage and Max Assassin as well as his "Terror Toons" DVDs who wants respect and world domination)
- Dante's Inferno (as Lucifer)
- Supernatural (as Lucifer)
- Devilman(Satan is an angelic Hermaphrodite)
- Touhou The Last Comer (It's specified that Mumumu Mikaboshi is not an avatar like many other characters in the series, but the true devil).
- The Devil also appears in animal form in the 1996 animated film All Dogs Go to Heaven 2 where it is depicted as a cat demon called Red.
The Devil is a popular figure in folklore and has appeared in countless legends around the world. A folk Devil is often more of a trickster than a malevolent embodiment of pure evil but at the same time is often seeking the souls of unfortunate mortals via trickery: many haunted places in the world are said to have connections with Satan or the Devil and some areas are even named after him - a famous example of Satan in folklore is the Jersey Devil (said to have been created when a woman yelled out "let it be the Devil!" when pregnant with a baby, to her surprise she got her wish).
- Angra Mainyu
- Loki (mythology)
- The Beast (religion)