The Devil is the name given to a supernatural entity, who, in most Western religions, is the central embodiment of evil. This entity is commonly referred to by a variety of other names, including Satan, Asmodai, Beelzebub, Lucifer and/or Mephistopheles. In classic demonology, however, each of these alternate names refers to a specific supernatural entity.
Some scholars believe that the notion of a central supernatural embodiment of evil, as well as the notion of angels, first arose in Western monotheism when Judaism came into contact with the Persian religion of Zoroastrianism. Much like classical monotheism, Zoroastrianism has one supreme God, and an evil spirit who chose to be evil, locked in a cosmic struggle where both are more or less evenly matched, though from the beginning Ahura Mazda's triumph is foretold; making Zoroastrianism an ethical dualism. Ahura Mazda ("Wise Lord"), also later known as Ormazd in Middle Persian, is the God of light, or Truth, and Angra Mainyu ("Evil Spirit"), also later known as Ahriman in Middle Persian, is the primeval Spirit of darkness, or the Lie. In a final battle between the forces of good and evil, human souls will be judged in a fiery ordeal of molten metal where the good will pass through as if it were warm milk and those who chose evil will be purified and all will be reunited in the new perfected world. Accordingly, humans are urged to align themselves with Ormazd and his Yazatas ("angels") and to shun His adversary who is the ruler of darkness and his demons, so that they may facilitate the final renovation (Frashō-kereti).
Christianity views Satan as an angel cast from heaven by God, for being prideful, deceitful, and the tempter.
The English word devil derives via Middle English devel and Old English dēofol and Latin Diábolus, from Late Greek Diabolos, meaning, slanderer, from diaballein, to slander: dia-, across + ballein, to hurl.
Concept of the devil in world religions
In Christianity, the Devil is named Satan, sometimes Lucifer. He is a fallen angel who rebelled against God, and has been condemned to Hell. In the Bible, he is identified with the serpent in the Garden of Eden, the Accuser of Job, the tempter of the Gospels, and the dragon in the Book of Revelation. Many modern, liberal Christians view the devil metaphorically.
In Islam the Devil is referred to as Iblis, which is Arabic for Lucifer, and is also called Satan (Arabic: Shaitan) (a word referring to evil devil-like beings). According to the Qur'an, God (called Allah in Arabic) created the Devil out of "smokeless fire", while He created man out of clay. The primary characteristic of the Devil, besides hubris, is that he has no power other than the power to cast evil suggestions into the heart of men.
According to the verses of the Qur’an, the Devil's mission until the Qiyamah or Resurrection Day (yaum-ul-qiyama) is to deceive Adam's children (mankind). After that, he will be put into the fires of Hell along with those whom he has deceived. The Devil is also referred to as one of the Djinns (genies), as they are all created from the smokeless fires. The Qur'an does not depict Shaitan (English: Satan) as the enemy of God, for God is supreme over all his creations and Iblis is just one of his creations. Unlike the Zoroastrian beliefs, all good are from God Himself and only he can save humanity from the evils of his universe and His creations. All bad deeds are done by our choice. Satan's single enemy is humanity. He intends to discourage humans from obeying God. Thus, humankind is warned to struggle (jihad) against the mischiefs of the Satan and temptations he puts them in. The ones who succeed in this are rewarded with Paradise (jannath ul firdaus), attainable only by righteous conduct.
He was expelled from the grace of God when he failed to pay homage to Adam, the father of all mankind. He claimed to be superior to Adam, on the grounds that man was created of earth unlike himself. Even the other angels showed a degree of suspicion when God informed them about the creation of man as the regent (caliph) of all things on Earth, but they ultimately prostrated before Adam to show their homage. However, Iblis, adamant in his view that man is a worthless being, never bowed his head before any other than God. This caused him to be expelled by God, a fact that Iblis blamed on humanity. Initially, the Devil was successful in deceiving Adam, but once his intentions became clear, Adam and Eve repented to God and were freed from their misdeeds and forgiven. God gave them a strong warning about Iblis and the fires of Hell and asked them and their children (humankind) to stay away from the deceptions of their senses caused by the Devil.
In Hebrew, the biblical word ha-satan means adversary or obstacle, or even "the prosecutor" (recognizing that God is viewed as the ultimate Judge).
In the book of Job (Iyov), ha-satan is the title, not the proper name, of an angel submitted to God; he is the divine court's chief prosecutor. In Judaism ha-satan does not make evil, rather points out to God the evil inclinations and actions of humankind. In essence ha-satan has no power unless humans do evil things. After God points out Job's piety, ha-satan asks for permission to test the faith of Job. The righteous man is afflicted with loss of family, property, and later, health, but he still stays faithful to God. At the conclusion of this book God appears as a whirlwind, explaining to all that divine justice is inscrutable with human intellect. In the epilogue Job's possessions are restored and he has a second family to replace the one that died.
The Hebrew word for evil used above is usually translated as 'calamity', 'disaster' or 'chaos'.
In contrast to the Christian traditions and Islam, Hinduism does not recognize any central evil force or entity such as the Devil opposing God but does recognize that different beings (e.g., asuras) and entities can perform evil acts and cause wordly sufferings.  Prominent asura is Rahu whose characteristics are similar to Devil's.
However, Hindus, and Vaishnavites in particular, believe that Vishnu incarnates to destroy evil when evil has reached its maximum. Additionally, the problem of evil is mostly explained by the concept of Karma.
To be more specific, Hindu philosophy defines that the only existing thing (Truth) is the Almighty God. So, all these devils are very inferior cadre and mostly because of mental imagination. Asuras are also different people with bad motivations and intentions. Different species like siddha, gandharva, yaksha etc. are defined in the Hindu mythology which may not fall directly into mankind but treated as slightly superior to man. The main difference from other religions to Hinduism is that no devil has enough power to face God.
A "devil"-like figure in Buddhism is Mara. He is a tempter, who also tempted Gautama Buddha by trying to seduce him with the vision of beautiful women who, in various legends, are often said to be Mara's daughters. Mara personifies unskillfulness, the "death" of the spiritual life. He tries to distract humans from practising the spiritual life by making the mundane alluring or the negative seem positive. Another interpretation of Mara is that he is the desires that are present in ones own mind preventing the person from seeing the truth. So in a sense Mara is not an independent being but a part of ones own being that has to be defeated.
There is no Devil in Ifa. There is Esu or Elegba who is seen as a trickster. Christian missionaries attempted to equate the Devil with Esu. Odu Ifa teaches that "evil" as it were, is the result of the actions of people. Oldumare being omnipotent is capable of being good and evil. Thus in Ifa evil can be seen "relatively" to something else.
Khemet (Ancient Egypt)
While the term "devil" is not used in ancient Khemet the term Set, the name of Horus' "enemy" lends itself to the character known in the previously mentioned religions "Satan". In the Ausarian drama we find that Ausar (Greek: Osiris) is chopped into 13 pieces by Set. Auset (Isis) collects all of his pieces save his phallus. Horus, son of Ausar and Auset sets out to avenge the death and dismemberment of his father by confronting Set. Horus is victorious over Set and Ausar, being brought back from the dead becomes lord of the underworld. It is this drama that gives us the cosmic conflict between good and evil, evil being embodied by Set. This is not to say that Set was always seen as an evil character in Khemetic theology. There are many times in Khemetic history where conflicts between different "houses" lead to the depreciation of one neter relative to another.
In Neopagan religions that have assimilated aspects of Abrahamic mythology into their own pantheons, Satan, Lucifer, and Beelzebub are often seen as distinct and separate beings who perform necessary cosmic functions.
In Stregheria, the Lucifer/Satan connection is upheld just as in Christian mythology. The Streghe see Lucifer (the name "Satan" is never used in Stregheria) as a kind and philanthropic deity who chose to disobey the tyrant-god of the Christians by appearing in the form of the serpent to offer knowledge of good and evil to humans (presumably via the Tree of Knowledge of Good and Evil, as this is an allusion to the Genesis myth) in order to expose the Abrahamic God for the evil being he truly was. Stregheria's classical influence is apparent here, as in Greek mythology the serpent was seen as a symbol of wisdom.
Christian tradition has frequently identified pagan] religions and witchcraft with the influence of Satan. In the Middle Ages, the Church accused alleged witches of consorting and conspiring with Satan. Several modern conservative Christian writers, such as Jack Chick and James Dobson, have depicted today's neopagan and witchcraft religions as explicitly Satanic.
In fact few neopagan traditions recognize Satan or the Devil per se. However, many neopagan groups worship some sort of Horned God, for example as a consort of the Great Goddess in Wicca. These gods usually reflect mythological figures such as Cernunnos or Pan, and any similarity they may have to the Christian Devil seems to date back only to the 19th century, when a Christian reaction to Pan's growing importance in literature and art resulted in his image being translated to that of the Devil.
New Age movement
Participants in the New Age movement have widely varied views about Satan, the Devil, and so forth. In some forms of Esoteric Christianity Satan remains as a being of evil, or at least a metaphor for sin and materialism, but the most widespread tendency is to deny his existence altogether.
Lucifer, on the other hand, in the original Roman sense of "light-bringer", occasionally appears in the literature of certain groups as a metaphorical figure quite distinct from Satan, and without any implications of evil. For example, Theosophy founder Madame Blavatsky named her journal Lucifer since she intended it to be a "bringer of light."
Many New Age schools of thought follow a nondualistic philosophy that does not recognise a primal force for evil. Even when a dualistic model is followed, this is more often akin to the Chinese system of yin and yang, in which good and evil are explicitly not a complementary duality. Schools of thought that do stress a spiritual war between good and evil or light and darkness include the philosophy of Rudolf Steiner, Agni Yoga, and the Church Universal and Triumphant.
Social and Political Uses of the Devil Concept
People put the concept of the Devil to use in social and political conflicts.
People sometimes link their enemies to the Devil. Here are some examples:
Against the Roman Papacy, an Institution of the Devil: a pamphlet written by Martin Luther in 1545. Luther likewise was portrayed by the Roman Catholic Church as a disciple of the Devil. 
The concept of reason was referred by Martin Luther as "The Devil's whore".
white devil: a term used by the Nation of Islam to refer to white Americans
Great Satan: a term used by Iran to refer to the US.
Explain others’ beliefs
One can use the concept of the Devil to explain why others hold beliefs that one considers to be false and ungodly. Here are some examples.
In 2002, Rev. Jerry Vines referred to Muhammad as a demon-possessed pedophile. 
Fundamentalist pamphleteer Jack Chick portrays Satan as influencing or even controlling the Roman Catholic Church.
Dr. Henry Morris wrote that Satan originated the concept of evolution. 
The devil in literature
Many writers have incorporated the character of Satan into their works. Among the most famous are:
The devil in music
A few songs that make reference to the Devil are:
The Devil is a common theme in an extreme form of underground music known as black metal.
The musical interval of an Augmented 4th is sometimes known as "The Devil In Music", a name given to it circa. 1400, given its unusual sound. Composers were encouraged to stay away from the interval, and whilst it is sometimes found in non-religious music of the time, it was never used in religious music until the existing system of keys came into use.
The devil in film and television
Many films and television programs have portrayed the Devil in one form or another. Among these are:
The devil in video games
As with films, the Devil (or some nearly identical character) has appeared in numerous video games. A few of them are:
It should also be noted that the main villain of Shadow the Hedgehog, called Black Doom, has a final form called Devil Doom.
Also known as