Eidolons: In Greek mythology, eidolons are spirits of the dead that possess people. From the stories told about them, it seems like they can be a specific dead person with a life history possessing a living person, OR it come across as a more generic possession (such as Christian stories of demons possessing people). In either case, the person being possessed isn’t aware of their situation. Fun. Sidebar: Walt Whitman wrote a poem. In The Mark of Athena, there seem to be three specific eidolons tasked by Gaea to ruin our heroes’ lives. They possess various characters and eventually resort to possessing movable objects. Fun. 5/5 Monstrous Rating for being terrifying and really hard to defend against!
Phorcys and Keto: What I love about these two is that they’re not just any old god and goddess of the sea (there are a lot of sea-deities and nymphs! SO MANY), but specifically represent the dangers of the sea and the monsters inside it. In The Mark of Athena, they’re more like caretakers or circus masters, having a vast collection of monsters that they can send after their enemies at will. In themselves, they aren’t very scary or smart. 3/5 Monstrous Rating for not taking full advantage of these cool deities.
Icthyocentaurs: Specifically named Bythos and Aphros, these are essentially fish-centaurs: kinda like mermaids but with more horsey features. They’re related to Chiron, most famousest of centaurses. I had never heard of them before and I demand more icthycentaur-centered stories! Bythos and Aphros live in colony of mer-people in The Mark of Athena, and rescue some of our heroes when they almost get eaten by a seamonster (see below). They claim to be trainers of champions, just like Chiron, only we haven’t heard of them because they’re ocean heroes. I love that Aphros doesn’t train martial arts of any kind, mostly just home ec. What a hero. 4/5 Monstrous Rating even though they’re more like precious sea creatures.
Skolopendra: This is a very large sea monster that may or may not resemble a giant crayfish. Or a giant millipede. It’s gonna be a no from me. The demigods in The Mark of Athena have to fight one and resort to blowing it up with Greek fire. Typical. 4/5 Monstrous Rating.
Achelous: Achelous was a river-god who fought Hercules for the right to marry a beautiful maiden named Deianeira – so, yes, pretty typical myth story, especially when Hercules is involved. Achelous typically took the form of a snake or a bull but Hercules wrestles the bull-form and defeats Achelous, tearing off one of his horns in the process. This horn is turned into the Cornucopia, horn of plenty, by the river-nymphs (keep that in mind next time you watch The Hunger Games). Achelous holds a grudge, as you can imagine, and tells the whole story to Theseus later. My question is, what happened to Deianeira (answer: nothing good). In The Mark of Athena, Jason and Piper are sent on a quest by Hercules to get Achelous’ other horn because Hercules is a resentful dirt sack. In this story, Achelous is a bull with a man’s face. And yes, they get the horn. 3/5 Monstrous Rating.
Ephialtes & Otis: These two giants are the kind of rabble-rousing teenagers that you just have to shake your head at. They did stupid things like trapping Ares (the god of WAR, okay!) in a jar, and threatening to make a pile that would make it to heaven, and then they decided to kidnap Hera and Artemis to be their wives. Artemis ran from them in a form of a deer and tricked them into spearing each other. Because that’s what happens when you try to kidnap the maiden goddess of the hunt. I like them even less in The Mark of Athena, where they mostly fight with each other and try to one-up each other and/or their nemesis Dionysus. Being giants, however, they’re very difficult to defeat by mere demigods. Giants, man. 3/5 Monstrous Rating for the tutu.
Chrysaor: This guy has one hell of an origin. So Medusa and Poseidon hooked up that one time, right, and Athena was mad because it was in her temple, so Medusa became the Gorgon with snake-hair. When Perseus chops off Medusa’s head, two kids spring out of her head from the hook-up with Poseidon: Pegasus (yes, that Pegasus) and Chrysaor. Everyone has heard of Pegasus, almost no one has heard of Chrysaor. None of my sources can even agree on who this guy is! He might be a giant, OR he might be a winged boar. In The Mark of Athena, he is a guy with a golden mask who has turned into a pirate because he has nothing better to do and no one has heard of him. He’s REALLY good at swordplay and defeats Percy. His pirate-crew is made up of the sailors that Dionysus turned into dolphins that one time. 4/5 Monstrous Rating for being really obscure and tying in some Dionysus fun-times.
Arachne: Her backstory is well-told in The Mark of Athena, but in summary: Arachne was a beautiful young woman who was extremely skilled in weaving and had a great deal of hubris (FATAL FLAW). She claims to be as good as Athena (or Minerva). Athena goes to her and warns her not to be over-confident, but instead Arachne challenges her to a contest. They both make amazing tapestries; Athena weaves images of her rivalry with Poseidon (Neptune), whereas Arachne chooses images of embarrassing moments or failures of the gods. Athena is pissed off and turns Arachne into a spider; no one is surprised. In The Mark of Athena, Arachne is a giant monster-spider, and she has been taking out her revenge on Athena’s half-mortal children for centuries. Rude. But she makes a great Big Bad. 5/5 Monstrous Rating.
Bulfinch, Thomas. Bulfinch’s Greek and Roman Mythology: The Age of Fable. Dover Thrift, 2000. Print.
Hamilton, Edith. Mythology. New American Library, 1969. Print.
Riordan, Rick. The Mark of Athena. Disney Hyperion, 2012. Print.
See also the links above for more sources!