A 17th-century occultist copying a grimoire by candlelight faced a decision. The text before him named a king of hell: Asmoday. But the Bible he knew called that same figure Asmodeus. Were they the same? Different? Did it matter for the ritual? He chose to keep both names in the margin, a hedge against error that generations of practitioners would inherit.
Asmoday and Asmodeus are the same entity. The difference is entirely a matter of which textual tradition you are reading. Asmoday is the name given in the Ars Goetia, the first book of the Lesser Key of Solomon (compiled circa 1640). Asmodeus is the older name, appearing in the Book of Tobit (circa 200 BCE) and later Christian demonology. One entity. Two cultural filters.
Where the Names Come From
The older name is Asmodeus. It appears in the Book of Tobit, a Jewish text from the Second Temple period (circa 225–175 BCE) that was preserved in the Catholic and Orthodox biblical canons. In Tobit 3:8, Asmodeus is the demon who kills Sarah’s seven husbands on their wedding nights before the marriage can be consummated. The name likely derives from the Avestan Aēšma-daēva, meaning “demon of wrath,” a figure from Zoroastrian Persian religion. That etymology places the name in the 6th century BCE or earlier.
Asmoday is a Latinized corruption of Asmodeus that appears in the Lemegeton manuscripts of the 17th century. The earliest known manuscript of the Ars Goetia (Sloane MS 3825, dated to approximately 1640) spells it Asmoday. The spelling shift is typical of grimoire transmission: scribes working from memory, from oral tradition, or from damaged manuscripts produced variant spellings that then became fixed in their own lineages.
The two names never appear together in the same primary source. They are separated by roughly 1,800 years and by fundamentally different religious frameworks.
What Each Tradition Says About the Entity
The Book of Tobit gives Asmodeus a specific story and a specific weakness. He is a jealous demon who loves Sarah and kills every man who tries to marry her. The archangel Raphael instructs Tobias to burn a fish’s heart and liver on their wedding night. The smoke drives Asmodeus away to “the remotest parts of Egypt,” where Raphael binds him. This is a folk exorcism narrative: a named demon with a named countermeasure, operating within a monotheistic framework where God’s angels have final authority.
The Ars Goetia gives Asmoday a different portrait entirely. He is a king of hell, ruling 72 legions of spirits. He appears with three heads (a bull, a man, and a ram), a serpent’s tail, and goose feet. He breathes fire. He rides a dragon and carries a banner and a lance. His office is to teach geometry, arithmetic, astronomy, and handicrafts. He makes the magician invisible. He reveals hidden treasures. He gives the “ring of virtues.”
The difference is not contradiction. It is genre. Tobit is sacred narrative. The Goetia is operative magic. One tells you what the demon did. The other tells you what the demon can do for you.
How the Two Names Survived Side by Side
By the 19th century, occultists had access to both traditions. S.L. MacGregor Mathers, co-founder of the Hermetic Order of the Golden Dawn, translated the Ars Goetia in the 1880s. He used the name Asmoday but noted the connection to Asmodeus in his annotations. Aleister Crowley published an edition in 1904 that kept the Goetic spelling but referenced the Tobit narrative in his commentary.
Modern demonological reference works handle the split differently. Some treat Asmoday and Asmodeus as separate entries with cross-references. Others treat them as a single entry with a note on orthographic variation. The Dictionary of Demons by Michelle Belanger (2010) lists Asmodeus as the primary entry and notes Asmoday as a variant. The Encyclopedia of Demons and Demonology by Rosemary Ellen Guiley (2009) does the reverse.
There is no scholarly consensus because the question is not factual. It is taxonomic. Do you classify by name or by entity? If by name, they are different. If by entity, they are the same.
What Practitioners Actually Do With the Distinction
In contemporary ceremonial magic, the choice of name signals which tradition you are working from. Calling the entity Asmoday places you in the Goetic lineage. You are working with the Lesser Key framework: the brass vessel, the circle, the triangle, the specific conjurations attributed to Solomon. Calling the entity Asmodeus places you in the Solomonic or Christian exorcism lineage. You are working with the Book of Tobit framework: prayer, angelic authority, the burning of fish parts.
Practitioners who work with both traditions often use the Goetic name for evocation and the Tobit name for banishing. The logic is functional. Asmoday is a spirit you call into a triangle to answer questions. Asmodeus is a demon you drive away with smoke and the name of Raphael. The same entity, but the ritual posture is opposite.
Some modern occultists reject the distinction entirely and use the names interchangeably. Others insist on precision. The debate is not theological. It is about what works in practice. And since no two practitioners get identical results, the debate never resolves.
Why the Confusion Matters
The confusion between Asmoday and Asmodeus is not a trivial spelling error. It reflects a deeper tension in Western occultism between sacred text and grimoire tradition. Sacred texts (the Bible, the Apocrypha) treat demons as enemies to be defeated by divine power. Grimoires treat them as resources to be exploited by ritual skill. The same entity cannot be both without a shift in how you understand what a demon is.
If Asmodeus is a demon who kills husbands out of jealous love, he has agency, desire, and a narrative arc. He is a character in a story. If Asmoday is a king of hell who teaches astronomy and reveals treasure, he is a function in a system. He has no story. He has a job description.
The difference between Asmoday and Asmodeus is the difference between a demon you pray against and a demon you work with. That is not a small difference. It is the central divide in Western demonology.
Common Misconceptions
Asmoday and Asmodeus are different demons. They are the same entity filtered through different textual traditions. No primary source treats them as separate beings.
Asmodeus is a fallen angel. The Book of Tobit does not describe Asmodeus as a fallen angel. That identification comes from later Christian demonology, particularly the Testament of Solomon (circa 1st–3rd century CE), which retroactively fits Asmodeus into the angelic rebellion narrative.
Asmoday is a corruption of Asmodeus. The direction of corruption is from Asmodeus to Asmoday, but “corruption” implies error. It is more accurate to say the name evolved through oral and scribal transmission within a different ritual context.
You can summon Asmoday using the Book of Tobit. The Book of Tobit does not contain conjurations. It contains a narrative of exorcism. The conjurations for Asmoday come from the Ars Goetia, which is a separate text with a separate ritual system.
FAQ
Is Asmoday in the Bible? No. The name Asmoday does not appear in any biblical text. The name Asmodeus appears in the Book of Tobit, which is part of the Catholic and Orthodox biblical canons but not the Hebrew Bible or Protestant Old Testament.
Can you summon Asmodeus using Goetic methods? Practitioners disagree. Some use the Goetic conjurations with the name Asmodeus and report success. Others insist the name must be Asmoday for the ritual to work. There is no empirical way to settle this.
Which name should a beginner use? Use Asmoday if you are working from the Ars Goetia. Use Asmodeus if you are working from the Book of Tobit or Christian exorcism traditions. Using the wrong name for the wrong framework invites confusion, not danger.
Does the spelling affect the ritual? It affects the ritual’s textual authority. Using Asmoday aligns you with the Goetic manuscript tradition. Using Asmodeus aligns you with the biblical tradition. The entity does not care about spelling. The tradition does.
The difference between Asmoday and Asmodeus is not a fact to be memorized. It is a choice to be made. Every practitioner who opens a grimoire or a Bible makes that choice, whether they know it or not. The name you use determines the tradition you inherit, the rituals you perform, and the relationship you have with the entity you call.
We keep both names in our library. We do not resolve the tension. We document it.
For a deeper look at the full hierarchy of Goetic spirits, see our guide to demonology and the Goetia. For the specific sigils and conjurations of the 72 spirits, see our guide to the Ars Goetia. For the relationship between biblical demons and grimoire spirits, see our glossary entry on demonology.