They were an original alternative to the use of the Kraken in the show. However, they were not used either, since the show was cancelled too soon. Serpentongues were thought as huge (as large as a little island) half-worm half-fish monsters. Their name comes from the fact that when they opened their mouths, hundreds of sea serpents came out (each serpent bigger than a regular pirate ship). They are probably based in the Leviathan, an enormous sea dragon and demon king.
A reason why they maybe were not used in the end is because due to their excessive size; they could have been too overpowered and nearly impossible to kill. Another reason could have been because of budget issues, and the difficulty of making puppets of these creatures.
The original concept was making him some sort of bounty hunter who Horace would have summoned to end the Laughingstock. He would have behaved as an eccentric drama actor with blades instead of fingers and two masks: a "comedy" mask in his face and a "tragedy" mask in his nape. He was also intended to talk in old-fashioned English, usually referencing Shakespeare's plays.
However, the design of the character implied it to be a living shadow with a thin, harlequin-like body that the shadow would have control over like a puppet. The technical implications made it nearly impossible to do with the resources of that time.
According to The Fascinating Creatures of the Abyssal Kingdom, "It is a playful little cat-like creature that Abyssians often keep as pets...unfortunately, it's claws drip with poison that would be deadly to a non-Abyssian. However, according to the abyssians, the poisonous substance is a favorite for certain delicacies. It is a shame we were obviously unable to sample these delicacies, as the inhabitants described them as tasting sweet with a tinge of spice to it. They like to eat rabbits, and enjoyed the dried salted fish we brought with us on our trip."
The concept art showed them as purple cats (about up to an average person's waist) with no visible mouths.
The Skin-Taker was originally going to have one as a pet, but the clay model that was going to be used was lost, although some believe that it appeared briefly in The Birthday Party.
Thin Ink Face People
They are strange creatures, very thin with black ink dripping from their faces.
Not much is known about these, except that the development crew was going to use baby dolls with smiles drawn on them, and that they would cause mayhem. According to the documents in the development stage, they would have had cried like babies, but never stop smiling while doing so. Even The Fascinating Creatures of the Abyssal Kingdom is unclear of exactly what these things do. They may not have been included in the show because the development staff could not decide their purpose.
They are a species who eat human (and Abyssian) flesh. They are intelligent, although quite brutish. They are tall, greasy, and often have rotten teeth. They also have antlers and tails. The length of their tail determines their rank in their society, with shorter tails being higher rank.
Not all Cannizars eat human flesh, as many prefer to make their own cooking concoctions from other edible animals such as chickens, pigs, and rats. Rabid squirrels are a delicacy, since they are immune to rabies.
Black Teeth actually was a Cannizar, but his species is not described in the series.
They are very common, and large in number. They are created by a type of parasite called a Skren that possesses the bodies of other monsters, and transforms them from the inside out, until it takes the form of a Skrenton. Not much is known about it. It is believed the Skren is an invasive species illegally brought to the Abyssal Kingdom from some far away land. Sometimes part of the skull will break, and the Skren will leak out of it a little.
The Skren appears to be a mass of tentacles attached to a brain. They can survive for years without food or water on their own. However, the brain looks very different from regular brains, they are less constructed, and look as if they were randomly scrambled together, probably as a result of the skren having to drag itself around until it finds a host body.
The Skren enters the body of it's victim, then works towards it's brain. The Skren will slowly disconnect the brain from the spine. It will then connect itself to the spine, and eat away the brain.
At this point, the Skren has completely replaced the brain, and is in full control of the body. The skren will then send signals to the rest of the body to transform it into a shape and appearance that pleases it. As a result, Skrentons come in many shapes and sizes, but most are grey due to being from the Abyssal Kingdom.
The Crawl was a unused large spider monster puppet believed to be the Skin Taker's pet but its design was deemed too frightening to air on show by the network.
The Jackal Barrel Bunch
The Jackal Barrel Bunch were going to be antagonists during the second season. They were jackal-like inappearance, and often robbed other pirates.