Satan is the Greater-Scope Villain or Big Bad of most varieties of Christianity and Islam (and by extension of most settings in which he is confirmed to exist), and a fair amount of fiction with religious influences, and other religions have similar variants. Traditionally, he is the single most evil being in existence, period.

Known also as... Helel (supposedly his original angelic name, which in Hebrew literally means "shining one" and metaphorically means "morning star") or Lucifer (Latin translation for the word Helel, which literally means "light bringer"), Samael (another angelic name often attributed to him, Hebrew for "Poison of God"), Beelzebub (Hebrew for "Lord of Flies"), Iblis, the Father of Lies, the Prince of Darkness, "the Other Guy", Old Scratch, Old Nick, the Quare Fellow, Lucifer Morningstar, Spooky Electric, Basement Cat... or simply the Devil. Also has a number, which is 666. Should you encounter someone with any of these names, run away.^note Though the authenticity for some of these names for Satan is still a subject to debate to this day.

Satan's backstory casts him as a Fallen Angel, originally the light-bearing archangel of Heaven, who is damned to spend eternity in Hell due to his rebellion against God. By virtue of his once-grand celestial position, Satan is depicted as the ruler of Hell and the demons that dwell, even if he's as much a prisoner there as any of the damned. This backstory is derived from the Book of Revelation in The Bible.

No matter what version of Satan is employed, he is usually a shapeshifter, capable of taking any form — physical or not — that he cares to. In human form, he is often shown with red or blond hair. His true form is often that of a Big Red Devil, or perhaps a snake or dragon. All things that hide or distort the truth are in his province, making him also the master of deception and illusion. Consequently, his most common incarnations are wheeler-dealers, bargainers, and con-men.

Due to this, Satan is frequently used to represent any threat (real or perceived) to a community's stability and its moral integrity, often appearing as an Unreliable Narrator who seeks to trick mortals into thinking that sin, various vices, and other "evil" beliefs are in fact harmless, or even good all along despite what God wants them to think. Far too often, however, he tends to be used as a strawman by Moral Guardians for the purpose of invoking Hitler Ate Sugar, whether claiming that any opinions they consider subversive of the social order are evil and wrong by default because Satan supposedly put them in the troublemaker's head (even when they aren't actually wrong in themselves), or demonizing whatever hobby of yours they don't like by claiming they are Satanic because he is involved in them. ^note  Or maybe this is what he wants you to think... Rock & Roll, drugs, new media, homosexuality, any foreign culture with a different set of values that goes against the Moral Guardians' beliefs, and generally any new fad that becomes popular among youngsters are especially prone to this, while the Everyone Is Satan in Hell phenomenon practically runs on it.

Despite an overwhelming overconfidence (he represents the Deadly Sin of Pride, after all), he almost always possesses a keen sense of enlightened self-interest. In keeping with the belief of the "most beautiful angel" who fell, Satan takes a handsome face whenever possible, but behind it is often rage and hatred; tearing away that mask, either intentionally or not, is possibly one of the most suicidal things a character can do.

In his more modern incarnations, he is often a charming Man of Wealth and Taste with a taste for the offerings of humanity's cultural achievements, from wine to music to poetry and stories. His interpretations do not always accord with the official ones. Despite this however, Satan is usually shown — for all his enjoyment of the finer things — to have a pathological hatred of humanity, blaming them for stealing the rightful place of the angels as God's children.

One of his favorite ploys (it's at least Older Than Steam, as seen in Faust and earlier) is to essentially grant one or more wishes in exchange for the wisher's soul. It's a classic lopsided deal in the Devil's favor — short-term corporeal gain in exchange for long-term infernal torment. This is almost always handled via a physical contract which is usually composed entirely of torturous legalese. Single wishes are almost always handled Literal Genie style, if not perverted outright. In some versions of the story the contracted victim may be able to free himself via a redemptive act or the intervention of God; in modern takes, especially Super Hero comics, the hero may take revenge against the Devil via a Faustian Rebellion. In any case, his goal is to lure as many souls to his side as possible, making him an example of The Corrupter.

In recent depictions, Satan is sometimes subverted by giving him an unexpected soft spot that renders him a bit more "human" and less supernatural—he likes kittens, or snowcones for example. It doesn't make him any less dangerous (if he's dangerous at all); it just lets the audience think they understand him.

Another common plot revolves around Satan's son, presumed to be The Antichrist. Some common subversions are that this child's just a normal person, or that he's smoking hot.

Satan is traditionally associated with a host of archdemonic sidekicks, among the best known of which are Mephistopheles, Azazel, Belial, Mammon, Moloch, Baal, Asmodeus, Beelzebub, and Lilith. These are sometimes seen as servants of Satan (often with more effective power over humans, presumably because their actions are not so closely watched), but are also (with the obvious exception of Lilith) often conflated into alternate names for the same being. Most of these names, as with "Lucifer", derive from supernatural figures from pre-Jewish beliefs in the Middle East, who were changed into devils as the new Abrahamic faiths took over.

To learn more about the history of Satan, visit the Analysis page.

Related to Satan is the Satanic Archetype, which is a (usually) original character explicitly modeled after him. They tend to have features such as being the lord of all evil in the world, rebelling against the supreme deity they served or the celestial beings that they were once a part of, or leading some race of demons or other evil creatures. If a series revolves around gods and goddesses, usually there will be one cast as a Satan figure in spite of how they were portrayed in the original mythology; this is a phenomenon called Hijacked by Jesus. This is why Everybody Hates Hades from the Greco-Roman pantheon, because he is assumed to be like Satan.

A common twist is that Satan Is Good, a victim of propaganda; see God Is Evil. Of course, sometimes God and Satan Are Both Jerks. A common portrayal in Western Media is also to cast Satan as The Anti-God, as God's Evil Counterpart, in contrast to most Christian theology, where Satan is a far lesser being than God. It has also become popular to portray the Devil without any reference to God.

He is generally the leader of The Legions of Hell and is an essential component of a Fire and Brimstone Hell. When hiding under an alias, usually a pretty transparent one, this becomes Louis Cypher. If there's more than one, we're talking about Demon Lords and Archdevils. You might be interested in his brothers as well, Archangel Michael, Archangel Gabriel, Archangel Raphael, and Archangel Uriel.

For when Satan rocks out, see Rock Me, Asmodeus!. If Satan threatens heteronormative gender roles in addition to your soul by being a Sissy Villain, Camp Gay, or a Creepy Crossdresser, see Flaming Devil.

Remember, this trope is about the use of Satan as a Public Domain Character. If the character shares several significant features with him but isn't at least implied to be the abrahamic Devil, they go under Satanic Archetype. If the character claims to be Satan when they literally are not, then it's a case of Devil Complex.

Examples:

• Anime & Manga
• Comic Books