Suggested resources for mythology

[Sacerdos]

And if you want to get a jump-start on the Atua, who I believe should be popping up in Demigod, check out Antony Alpers' "Maori Myths and Tribal Legends"

For a broader perspective on Polynesian mythology, also consider Alpers' "Legends of the South Sea", which includes translated myths from all over the islands. A more locally focussed as well as dense, but very complete approach is Martha Warren Beckwith's "Hawaiian Mythology", which is available online (http://ulukau.org/elib/cgi-bin/libra...in&a=d&p2=book). While focussed on Hawaii, Beckwith's monumental work does a lot of comparison with material from the rest of Polynesia. And lastly, for short entries with extensive bibliography, look for Robert D. Craig's "Dictionary of Polynesian Mythology" (the same guy who did the "Handbook of Polynesian Mythology" for ABC Clio). It includes basically every name ever appearing in any Polynesian mythology.

Oh yeah, and because I forgot the Orisha before, I would try Ulli Beier's "Yoruba Myths" for a nice little collection of different myths (just don't get weirded out by the first two in the collection, they're not very ... standard) and E. Bọlaji Idowu's "Olodumare: God in Yoruba Belief" for a dated and biased, but still very important introduction. While Idowu focusses on belief in the Yoruba high god Olodumare, he works through a great amount of general religion and mythology in passing.

[Arlecchino]

And if you want to get a jump-start on the Atua, who I believe should be popping up in Demigod, check out Antony Alpers' "Maori Myths and Tribal Legends"

[Sacerdos]

Watcher has already mentioned Ashkenazi's "Handbook of Japanese Mythology, but I would actually recommend all of ABC Clio's "Handbooks of World Mythology" (Chinese Mythology, Classical Mythology, Egyptian Mythology, Hindu Mythology, Inca Mythology, Mesoamerican Mythology, Native American Mythology, Norse Mythology, Polynesian Mythology). All of them are at least good, some of them are great. They are all introductory material, of course, but relatively recent, and give a good overview over the most important figures and concepts in each of those cultures, along with brilliant introductions that outline cosmology and mythological time.

Regarding Egypt and the Ancient Near East, the University of Chicago has made a lot of its scholarly publications available online, including e.g. Allen's translation of the Book of the Dead. Apart from that, I would advise you to stay away from the older translations of Egyptian texts online, especially those by Budge, because they're horrifically outdated. Miriam Lichtheim's three volumes of Ancient Egyptian Literature include translations of all the most important Egyptian religious material (as well as lot of other Egyptian writing you'll probably be less interested in), so I'd look to that.

With Norse mythology, there's Northvegr (http://www.northvegr.org/index.html) and Germanic Mythology (http://www.germanicmythology.com/), both of which are not perfect, because Northvegr uses many non-scholarly translations and Germanic Mythology very old ones. Still, the scope of those two sites is just so broad, I'm sure you can still profit from it. Also, here is an older translation of the Gesta Danorum, the often legendary history of the Danes by Saxo Grammaticus: http://omacl.org/DanishHistory/

For the Kami, I would add the Encyclopedia of Shinto (http://eos.kokugakuin.ac.jp/modules/xwords/), which, among others, has entries on a very broad array of deities. Although the focus is on Shinto, there is a lot of material on Buddhist elements, too, because those two are just inseperable in Japan, no matter how hard Emperor Meiji may have tried. The encyclopedia is provided by the Kokugakuin University, which trains Japanese Shinto priests, so it's a quite authoritative source.

For the Aztecs, there is also "The Gods and Symbols of Ancient Mexico and the Maya: An Illustrated Dictionary of Mesoamerican Religion" by Mary Miller and Karl Taube, which has an iconographical focus, and makes a great addition to the "Handbook of Mesoamerican Mythology". If you consider structualist approaches and looking for continuities between pre-Columbian and post-Colonial Mesoamerican religion valid, I found "Myths of Ancient Mexico" by Michel Graulich and "The Myths of the Opossum: Pathways of Mesoamerican Mythology" by Alfredo López Austin to be very enlightening.

Now, lastly, Hindu mythology is very problematic, because the old translations are often very inaccurate, but the newer ones are sometimes hard to get by. With the epics, I'm still looking for appropriate material myself, but with the legends of the Puranas, I recommend "Classical Hindu Mythology: A Reader in the Sanskrit Purāṇas" by Cornelia Dimmit as a rough overview.

If you want any more in-depth suggestions or I missed any culture you'd be interested in, feel free to message me.

[Watcher]

Brilliant question! You're right that you do need to be careful when searching for works, there are some out there that are especially trap-ish and you really need a good pre-existing grasp on things to notice there is something weird going on. Then there is also the problem that there was the whole Occultism craze during the Victorian period (and in the 1960s-70s a bit) that produced a whole lot of work we would treat as exceptionally dubious.

If you have any specific Pantheons you want to learn more about, people could probably give you more specific reading materials. But, I'll just give you a smattering of stuff for the Pantheons I have a vague grasp of.

Aesir
Now, I've not done much work with the Aesir, but there is a whole lot written about them thankfully. First thing you need to be cautious about is the neo-Nazis who sneak in if you're reading online. The Prose Edda, and The Poetic Edda are the big texts for the Norse. The Prose Edda is written by a Christian Monk during the Christianize period though, so a lot of humanization goes in in the texts so you need to read between the lines there. (de-deification. Making Gods into Humans) Also there is some weird stuff about Baldur and Ragnarok possibly being made up by that monk in trying to Christianize the stories but that's like this whole other kettle of fish.

• Prose Edda: This is a translation from the early 20th century. It's free, which is nice, but if you want a more modern version I would check out Penguin Classic's one done by Jesse L. Byock.
• Poetic Edda: Again, this is from the 1920s, so you need to be careful slightly. (mainly the introduction) But, it's free. For a more modern version, once again, Penguin's The Elder Edda done by Andrew Orchard is probably pretty good. (I like Penguin a lot. I think I have only encountered one of theirs I had issue with, and even then I am unsure if it was actually Penguin or just had a black-ish cover. Edit: It wasn't Penguin, just went and checked. Ignore this. Its introduction was just weird.)

Anunna
The legends of Mesopotamia are a must-read for like everyone since they're some of the oldest stories we have left and that's just neat. They have two big ones, one divine cycle, one more like a Scion story. The former, The Enuma Elish, the later, The Epic of Gilgamesh. Now, there are some problems. Firstly, we know these are not the entire stories. The Enuma Elish is on damaged tablets so we have huge tracts of text that we don't know what happens in. Furthermore, we know the story changed depending on which Mesopotamian Empire ruled at the time. Each empire liked to swap in their city's local Deity to be the Big Important One. So, for example, under Babylon they elevated Marduk. Now, with the Epic of Gilgamesh, just last year I believe some MA student translated a tablet (we have so many of them that we can't translate them all. Mostly tax records.) that expanded a short section of the story into this whole 'big' sub-adventure. But, anyways.

• The Enuma Elish: And also maybe this one. These are from Sacred Texts who are really good at providing some nice sources in searchable text. Now, not everything they have is 100% accurate, sometimes because it's outdated translations, sometimes because it's books on modern mysticism. But, not a bad spot at all.
• The Epic of Gilgamesh: Is just honestly a good read for everyone. It's the oldest piece of literature (I think, I have a vague feeling that I might be incorrect, but I think I'm confusing myself with the earliest known author instead of text) so you will probably be able to see a lot of common themes. Especially to do with Greece, there was a lot of Westward travel of deities from Mesopotamia. If you want a modern translation, Penguin again. I'm actually going to stop saying that since it carries true for most things I'll talk about here. They do good stuff.

Kami
Now, I want to start this with saying the Kami are not my cup of tea. I've done a lot of work on them for some house rules to revise them, but I have been carried by someone who knows far more about them than I do. I am going to give his reading suggestions here. Firstly, there is The Kojiki which is the Imperial Text for Japan. (By Imperial Text, I mean it's the text the Imperial Family used to justify their reign over everyone. So it's a very political document) Followed up by The Nihongi. But, honestly, these are a bit impenetrable, and The Kujiki is apparently more accessible while covering similar information. The Fudoki is a collection of local legends, however these are so local and rural they tell us pretty much nothing about the larger scale religious beliefs in the past. Then there are Shrine texts, which are tricky because every shrine likes to hype up their deity, (like the Babylonians hyping up Marduk in the Enuma Elish) and some are theological texts which are just complicated. And then there is Ashkenazki who wrote a encyclopedic text of the Kami (and Japanese Buddhism) who helped immensely.

• The Kojiki: I don't actually have a free digital version of this I can recommend. There is one on Sacred Texts, but the author was so Victorian he wrote the 'inappropriate' passages in Latin so women couldn't read them or something stupid. There are a lot of these passages. I used An Account of Ancient Matters The Kojiki by Gustav Heldt which is the most modern one I could find. (2014)
• The Kujiki: Again, no online source. I'm really sorry. This is what was suggested for myself though. "The Authenticity of Sendai Kuji Hongi: A New Examination of Texts, with a Translation and Commentary” by John R. Bentley."
• The Fudoki: Yeah, again, no online version. Some of these stories have been translated in "Records of Wind and Earth: A Translation of Fudoki with Introduction and Commentaries” by Michiko Y. Aoki."
• Shrine Texts: Now these are really cool. This source is specifically from one of Hachiman's shrines, and are about him thereby. It's done by a German University, and is honestly a really cool read. (Read the scrolls Right to Left. I didn't and was really confused until I was corrected.)
• My Man Ashkenazki: If you want to do Kami stuff, "Ashkenazki, Michael. Handbook of Japanese Mythology. Handbooks of World Mythology. Oxford University Press, 2008." This is a lifesaver.

The Netjer
I am not great with the Netjer. I don't know why, but I just have never had a chance to sit down and read them. While I can't give you documents, I can give you warnings. Remember how I talked about Victorian occultism? Yeah, they went seriously nuts for the Egyptians. Like, Making-Tea-From-Mummies nuts. You need to be really careful about everything you read about them from the late 19th - early 20th century. Furthermore, the Egyptians kicked around for ages, and had a huge amount of religious change as cults rose and fall. They have a lot of stuff. I have some resources I use for panic-research mid-game, but I don`t actually know enough about the topic to be sure on the quality. So, I`ll not link them here.

The Teotl
Everything I know about the Teotl, I know through Griff. I can't actually tell you the name of some texts to go read. I would ask him, but it's damn late, and he's probably asleep like a responsible person unlike myself who sits up at 3am writing forum posts. I'll do my best to remember to pass the question on to him tomorrow during game, but he might just read this before.

The Theoi
Just like Herkles said, Theoi.com is the most amazing resource. It's not really something you 'read' though. I need to look into who is doing it, but whoever they are, they're brilliant. They're organizing pages into collecting all of the relevant passages from primary texts. Wonderful, wonderful work. It isn't 100% finished at the moment but is awesome. (you can sneak onto some pages under construction by URL fiddling in the Cosmology section) If you want to read the actual texts, well, they're sort of well known in the Western World. The Illiad, The Odyssey, The Aeneid (though I personally really don't like this one. It's Roman Fan fiction), the Homeric Hymns, the Theogony, the Twelve Labors of Heracles, all the hero stories, the plays... there is a lot really. Theoi.com can direct you. You probably need to worry the least about translations of these texts too I would guess.

The Tuatha
Bringing up the rear are my favorite. Now, like I said with the Prose Edda, these documents have Been Fiddled With by early Christian writers. Don't be too hard on them, without these documents, we would know nothing about how awesome the Tuatha are and they'd go the way of the Gaulic Gods. Now, they have a lot of huge rhyming collections of text, legal code, place-names, but a lot of these are stupidly costly (the place-name translations haunt my dreams in how expensive they are.) or otherwise really hard to read. So, I'm going to say, go read Lady Gregory's works. She was a Victorian Lady (capital L) who traveled around Ireland actually listening to people and writing the stories down. She took the big Irish texts, and changed them from very tricky translated prose interrupted by family trees into narratives without losing much. Read these ones unless you're mental like me and want to stare at primary sources until your eyes bleed. Also, they're online because they're so old, which is great. Also: there is a lot of 'other' documents, but these are the 'big' ones (by this, I mean these are the ones most well known. If anything the Tuatha did is well known anymore really. These are the posterboys for Irish mythology). There are a lot of problems reading about the Tuatha online though, so much so I would actually recommend not reading anything online really. For whatever reason, the Celts have gotten a sort of weird following online, and there is a huge amount of misinformation. You need to be really careful with them.

• Gods and Fighting Men: Taken from The Book of Invasions / The Book of the Taking of Ireland, and then the Finnian texts. The first part are the stories of the Pantheon. Irish myth is divided into three sections, and the first part of this book is the Mythic Cycle. The second part is actually the third cycle, The Finnian Cycle, which is a lot like a story of Scions.
• CuChulain of Muirthemne: Taken from several sources (all somewhat partial IIRC), which collectively can be made out the story named The Tain Bo Cuailnge, or the Cattle Raid of Cooley (or just The Tain, but there are actually several different Tains so it's a bad name). This is the 'ending' of the Ulster Cycle, which is the second cycle of Irish Mythology. The story revolves around CuChulain, the Son of Lugh, who like Achilles dies young but will be remembered forever. Except CuChulain is super young.

If you want more Tuatha stuff, let me know. I've got a lot I could suggest.

Man, this post got super long. I hope it goes through.

Edit: I forgot the most important Tuatha warning. If someone starts going on about the druids, it's probably a dodgy source. The Druids are handy in that they attract a lot of attention, but we know next to nothing about them. So, if you have a book and the author is talking about what they do, it's probably not a great source.

Edit#2: I also have some sources on Wyandot mythology if you want them. They're really quite neat stuff. There are also some Pantheons left out - Oh I forgot to write about the Bogovi. Shoot. Okay, I'll do that below. But, the Shen, Orisha, Yazata, and Deva I do not know well enough to even open my mouth, so I'll just stay whisht.

The Bogovi
The Slavs are tricky since, like the Irish and Norse, their texts are recorded after the arrival of Christianity. However, it's even trickier with the Bogovi since they have a huge geographic area, and got Crusaded. Despite this, the Bogovi are a really cool Pantheon to include in games. They pretty much have a non-interventionist policy with mortals, and frequently break this causing inter-Pantheon problems. I have only encountered one nice source for it though, done by an ex-Minister of Culture I believe. It's a bit tricky to find though.

• Hudec, Ivan, Emma Nezinska, Jeff Schmitz, and Albert Devine. Tales from Slavic Myths. Wauconda, Illinois: Bolchazy-Carducci Publishers, 2000.

[Arlecchino]

You can also probably read all the extant Greek plays in less than a month. Again, Robert Fagles' translations are excellent.

[Arlecchino]

Irish: "Over Nine Waves" by Marie Heaney is a great, readable introductory source, if you can find a copy. She elaborates the Mythic, Finian and Ulster Cycles, as well as legends of the Irish Saints.

Greek and Norse: "The Usborne Book of Greek and Norse Legends" is a beautifully illustrated and surprisingly thorough book aimed at younger readers, but still makes a great intro for an adult new to the myths. If you're ready for original Greek sources, Hesiod's Theogony and Homer's epics (I like the Fagles translations) are your best bets.

For a nice world-myth sampler, check out Jason Weiser's Myths and Legends podcast.

[herkles]

For greek mythology, you can't go wrong Theoi.com. It has pretty much everything on Greek Mythology and Greek religion*. It has pages on pretty much every god and goddess, no matter how small. It lists everything, deified heroes, nymphs, monsters, titans everything. Also it has a digital library of the classical texts, from the Theogony, to the Illiad, to the Aeneid and more.

*As someone who practices Greek Polytheism or Hellenismos, Theoi.com is invaluable to me. Particularly for all the various Homeric and Orphic hymns.