Pathfinder Adventure Path’s “Bestiary” chapters are often a dress rehearsal for inclusion in the big books, but I’d be lying if I said I thought the galvo (from #59: The Price of Infamy) would make the cut. It’s a swarmlike creature made of electric eels—practically an eel golem (and you know my feelings on nontraditional golems)—that can “fire” component eels like darts. As such, it’s a natural servitor for eel-themed monsters like the siyokoy.
That said, the animal-headed-humanoid-hangs-out-with-the-animal-it-looks-like trope can get old after a while. (Gnolls hang out with hyenas! Ratfolk hang out with rats! Three-toed slothfolk hang out with three-toed sloths*!) So even though according to canon galvos are the work of siyokoy fleshcrafters, I’d rather see them paired with, say, gutaki (intelligent devilfish) or evil merfolk, just for variety’s sake.
I also think there’s a space for a galvo to be a really unique horror encounter, especially for a low-level party, a party unprepared for an aquatic encounter, or a character trapped alone. Imagine PCs’ only escape off of an island involves retrieving an object from a wreck in the center of the lagoon. But every time they get in the water, eels attack them—first one, then two, then several. Then dozens. Then the eels seem to emerge into a humanoid shape. And then it follows them on land…
Adventurers interrupt a tense exchange between lycanthrope toughs and ceratioidi smugglers. The ceratioidi, thinking they’ve been betrayed, bob their lantern-like stalks in an urgent semaphore. Immediately a tangle of galvos surges out of the pool in the center of the chamber, attacking any surface dweller they see.
Siyokoy will not settle where air breathers have drowned. But they will not give up their claim to these sunken treasure sites either. Adventurers who try to sneak into a sunken city by nightfall will be attacked by the galvos left behind as guards, supported by other fleshwarped creatures including aquatic, seaweed-like halsoras.
Adventurers explore the gut of an oma corpse drifting in space. Their efforts to find any survivors or treasure are hampered by the parasitic galvos still clinging to life inside the dead space whale’s digestive tract.
—Pathfinder Bestiary 4 120
*But never with two-toed sloths.
They know what they did.