Asmodeus is a king of demons from Hebrew mythology. Not found in the Hebrew bible, he is mostly known from the deuterocanonical Book of Tobit, in which he is the primary antagonist. The demon is also mentioned in some Talmudic legends, such as in the story of the construction of the Temple of Solomon.
Asmodeus would later become a prominent figure in demonology and the occult as one of the seven princes of Hell. In Binsfeld's classification of demons, Asmodeus is the demon of lust and is therefore responsible for twisting people's sexual desires.
In the Lesser Key of Solomon he "is strong, powerful and appears with three heads; the first is like a bull, the second like a man, and the third like a ram; the tail of a serpent, and from his mouth issue flames of fire." Also, he sits upon an infernal dragon, holds a lance with a banner and, amongst the Legions of Amaymon, Asmoday governs seventy two legions of inferior spirits.
The name "Asmodeus" in English is derived from the Latin name "Asmodaeus," which in turn was derived from the Greek name "Asmodaios," which in turn derived from the Hebrew name "Ashmeday," which in turn was derived from the Avestan "Aeshma-dæva." 
The term "Aeshma" translates to English as "anger" and is itself derived from the Proto-Indo-European term "*eismo-," which through it's root (*eis-) is etymologically related to terms in English such as "ire."
The word "dæva" which is derived from the Proto-Indo-European "*deiwos" meaning "god" and who's root "*dyeu-" means "to shine." Despite the origin of the term "dæva," it took on a negative connotation in Zoroastrian scripture, becoming synonymous with "demon," while maintaining it's positive connotation in other cultures.
Asmodeus in the Book of Tobit
The Book of Tobit was a religious text, in the form of a religious novel, that was written some time around the second century BCE. The book itself is named after the one of it's main characters, Tobit, who was a Northern Israelite living in exile in Nineveh, Assyria sometime around 722 or 721 BCE. This story was popular in both Jewish and early Christian communities, and is considered to be canon within Christian Orthodox and Catholic traditions, but non-canonical within Protestant traditions, thus making it a deuterocanonical text.
In the story, the wealthy and elderly Tobit is suffering from blindness and prays for death. At the same time, a young woman by the name of Sarah in the far-off land of Media (Northwestern Iran) is also praying for death because she'd been married seven times, with each of her husbands being killed by Asmodeus, the "King of Demons," on her wedding night.
As a result of God's intervention, Tobit remembers he has a large sum of money stored away in Media, and sends his son Tobiah to retrieve the money, with God sending the archangel Raphael to accompany Tobiah. While on his travels Tobiah reaches the Tigris River, where he's attacked by a large fish. Raphael orders Tobiah to kill the fish and harvest it's organs for use as medicine.
Later in the story, Tobiah meets Sarah and, with Raphael's insistence, marries her. On their wedding night Tobiah is attacked by Asmodeus, but following the instructions that were given to him by Raphael, he was able to use the fish's heart and liver to repulse Asmodeus, who retreated to upper Egypt, where he was captured and bound by Raphael.
Afterwards Tobiah returns to Nineveh with both Sarah and his father's large sum of money, and uses the fish's gall to cure his father's blindness.
Sakhr in Islam
In Islamic lore, Solomon banished him into a rock, after he takes his kingdom back from him. This is why he is known as Sakhr (Arabic: صخر the Rock or the Stony One). Solomon threw the rock to the bottom of the sea.
|The 72 Demons of The Ars Goetia|
|Kings||Asmodeus • Bael • Balam • Beleth • Belial • Paimon • Purson • Vine • Zagan|
|Dukes||Abigor • Aim • Agares • Allocer • Amduscias • Astaroth • Barbatos • Bathin • Buné • Berith • Crocell • Dantalion • Flauros • Focalor • Gremory • Gusion • Murmur • Sallos • Valefor • Vapula • Vepar • Vual • Zepar|
|Princes||Gaap • Ipos • Orobas • Seere • Stolas • Sytry • Vassago|
|Marquises||Amon • Andrealphus • Andras • Cimejes • Decarabia • Forneus • Gamigin • Leraje • Marchosias • Nebiros • Orias • Phenex • Ronové • Sabnock • Shax|
|Counts||Andromalius • Bifrons • Furfur • Halphas • Raum|
|Presidents||Buer • Botis • Foras • Glasya-Labolas • Marbas • Morax|
|Great Presidents||Amy • Camio • Haagenti • Malphas • Ose • Volac|