Hot damn this is getting even interesting! If you guys didn't know, every sigils you're solving across Hell are identified as actual sigils/seals from demons of Ars Goetia. Here's a chronological list:

1. Unknown. - The sigil is a heart with a large V symbol. Dunno if it's a demon's seal or not.

2. Buer - A Great President of Hell, having fifty legions of demons under his command. He teaches natural and moral philosophy, logic, and the virtues of all herbs and plants, and is also capable of healing all infirmities (especially of men) and bestows good familiars. The demon has the head of a lion and five goat legs surrounding his body to walk in every direction.

3. Raum - A Great Earl of Hell, ruling thirty legions of demons. He is depicted as a crow which adopts human form at the request of the conjurer. Raum steals treasures out of kings' houses, carrying them where he wishes, and destroys cities and dignities of men (he is said to have great dispraise for dignities). Raum can also tell things past, present and future, reconcile friends and foes, and invoke love.

4. Caim - A Great President of Hell, ruling over thirty legions of demons. Much detail is offered: he is a good disputer, gives men the understanding of the voices of birds, bullocks, dogs, and other creatures, and of the noise of the waters too, and gives true answers concerning things to come. He appeared in the form of the black bird called a thrush, but soon he changes his shape into a man that has a sharp sword in his hand.

5. Zepar - A Great Duke of Hell. He commands 26 legions of inferior spirits. His office is to cause women to love men, and bring them together in love. He makes women barren. He is depicted with red clothes and armor, like a soldier.

6. Forneus - A Great Marquis of Hell, and has twenty-nine legions of demons under his rule. He teaches Rhetoric and languages, gives men a good name, and makes them be loved by their friends and foes. He is depicted as a great sea monster.

7. Focalor - A powerful Great Duke of Hell, commanding three or thirty legions of spirits. Focalor is mentioned in The Lesser Key of Solomon as the forty-first of the 72 goetic demons. According to the grimoire: Focalor appears in the form of a man with a griffin's wings, kills men, drowns them, and overthrows warships; but if commanded by the conjurer he will not harm any man or thing.

8. Halphus - An Earl of Hell, commanding 26 legions of demons, who is said to have a rough voice when speaking. He is often depicted in the shape of a stork. Halphus builds towers and fills them with ammunition and weapons, an armorer of sorts.

9. Marchosias - A powerful Great Marquis of Hell, commanding thirty legions of demons. He is a strong and excellent fighter and very reliable to the conjurer, giving true answers to all questions. Marchosias hoped after one thousand and two hundred years to return to heaven with the non-fallen angels, but he is deceived in that hope. He is depicted as a wolf with a man's form as well as a griffin's wings and a serpent's tail, that under request changes shape into a man.

10. Furcas - A Knight of Hell, and rules 20 legions of demons. He teaches Philosophy, Astronomy (Astrology), Rhetoric, Logic, Chiromancy and Pyromancy. He appeared as a strong old man with white hair and long white beard, who rides a horse while holding a sharp weapon (pitch fork).

11. Sabnock - A mighty Great Marquis of Hell, who has 50 legions of demons under his command. He builds high towers, castles and cities, furnishing them with weapons, ammunition, etc., gives good familiars, and can afflict men for several days making their wounds and sores gangrenous or filling them with worms. Sabnock is depicted as a soldier with armor and weapons, the head of a lion, and riding a pale horse.