The Ars Goetia (often called just Goetia) is the first section of The Lesser Key of Solomon, an anonymously-written, 17th century book on demonology. It described 72 demons that King Solomon of the Hebrew Bible summoned, trapped, and enslaved. Each demon has its own seal. The subordinates of Ruby Eye Shabranigdu are roughly based on the demons of the Ars Goetia. See Plane chart for comparison.
Hellmaster Fibrizo is based on Astaroth, the Grand Duke of Hell and the 29th demon of the Ars Goetia. Astaroth is said to rule over the East; Hellmaster ruled over the Desert of Destruction, the eastern part of the mazoku barrier. Also, like Astaroth, Hellmaster presided over the souls in the underworld.
Chaos Dragon Gaav is based on Bune, a Great Duke of Hell and the 26th demon of the Ars Goetia. Bune takes the form of a three-headed dragon, as does Chaos Dragon. Some say that one of Bune’s heads is that of a human, and perhaps Chaos Dragon’s fate in human form reflects this.
Greater Beast Zelas Metallium is based on Ipos, a Prince of Hell and the 22nd demon of the Ars Goetia. Ipos takes the form of a chimera: the body of an angel, head of a lion, tail of a hare, and the feet of a goose. Greater Beast, by comparison, also has a chimeric form: the body of a soldier, the head of a wolf, and the wings of an angel.
Dynast Grausherra is based on Eligos, a Great Duke of Hell and the 15th demon of the Ars Goetia. Eligos is related to wars and soldiers, and he attracts rulers of nations. By comparison, Dynast disguised himself as the ruler of Dils. Supposedly Eligos appears as a handsome knight, and Dynast was reported to take this appearance in the Slayers novels.
Deep Sea Dolphin is based on Vepar, a Great Duke of Hell and the 42nd demon of the Ars Goetia. Vepar rules over the waters and controls the waves and currents. She has the appearance of a mermaid. Deep Sea rules over the Demon Sea.
Compare the Goetia sigils with the Plane Chart above. They’re different, but only slightly. What isn’t listed is that Bune actually has two seals, and is said to be able to command the dead (which got attributed to Hellmaster). I think one other of the Dark Lords has a second seal, but I can’t remember off the top of my head.
BTW, the runes that surround each Dark Lord’s sigil, spelling out their names, are a pretty random mix of all the runic alphabets (Elder Futhark, Younger Futhark, etc). Dolphin’s is especially mangled with regards to that.
The Plane Chart itself is based upon the chart above it. It’s from the Rorisicians (spelling?). You can see where the sigils for Death Fog and Chaotic Blue came from.
There are a lot of these things in Slayers. The alternate plane chart with the two-headed bird with the seals of the four Dark Lords on one side and the Shinzoku on the other. When Lina is waxing poetical about the “talented sorceress” that brought down the Mazoku Barrier to Gourry in the first episode of TRY, there’s a drawing of an angelic looking woman which is based on some old art.
And of course the Seal of Solomon in the original post. What’s interesting to note is that they changed the Oroborous in the original from a single snake to two snakes–which has it’s own symbolism. I have no idea is this was deliberate or if it was just something they thought would be cool. (Someone like me, though, finds hidden meaning in everything.)
Something interesting to note is that in that same episode of TRY, there’s a shot of the Barrier before it fell (during the same scene) and has the seals of the Dark Lords at the vertices of the barrier. However, in the anime they’re in the wrong locations (save for Hellmaster).