Monotheistic Religion

• The Bible Dictionary of Words and Phrases
• Glossary of Religious Terms
• Practicing Catholicism on slower-than-lightspeed generation colonization ships (FFA thread)

Pagan Mythology

• Godchecker
• Norse-Mythology.org
• Encyclopedia Mythica
• Women in Celtic Mythology

Legends & Folktales

• A List Of Arthurian Reference Materials and Resources for Writers
• Folklore and Mythology: Electronic Texts
• SurLaLune Fairytales
• Myth, Legend & Folklore
• Best of Legends
• Arcana Wiki: “Legends, mythology, UFO lore, Conspiracy theories, Fiction, and even (seemingly) mundane cultural traditions from other countries.”

Mythological Creatures/Fictional Species

• Mythical Realm
• Mysterious Britain & Ireland: Mysteries, Legends & The Paranormal
• Mythical Creatures & Beasts Wiki
• Pre-Dracula vampires
• Castle of Spirits
• Monstropedia
• List of Legendary Creatures
• Medieval Bestiary
• Mythical creatures //“from Scandinavian (especially Swedish) or possibly Russian folklore that a character could be in disguise”// (FFA thread)
• List of //Star Wars// species (FFA thread)
• How to hunt a basilisk (FFA thread)

Religious/Magical Worldbuilding (FFA threads)

• Fictional religions
• "Religions and worldviews in a world I'm building"
• Fictional religions
• Religion worldbuilding
• Afterlife myths
• Coming up with a magic system
• Classification of magic
• Harry Potter, magicbuilding, worldbuilding, and non-UK settings: first thread; second thread
• Knot-tying magic & folklore
• How to marry a god