This page serves as an introduction to common The Demon's Light terms.
- Atticus - Adopted son of Theo Rosington. Awoke in the Gladea barn with no memories.
- Aaron - John Fontaine's brother who joins the Search Party.
- Blackmore - Young member of the Svatovid that joined the Port City Eight at Headre.
- Baptiste - An Alchemilia Director of Robotics. Later became a Svatovid member.
- Blossom - Assistant at the Silivia Cognitive Science Center. Girlfriend of Atticus.
- Chris - An android created by Andrew Wellington.
- Charles - Chris' mechanical brother who cannot feel emotion.
- Dexter - A descendant of Andrew Wellington.
- Fontaine - Alchemilia Corporation operative.
- Gabriel - Infamous CEO of Alchemilia Corporation.
- Cicero - The only offspring of Xeren. He searches for the fragments of his father's soul.
- Jordan - Atticus's childhood friend who goes searching for him.
- Lisa - Atticus' ex-girlfriend who joins the Search Party to find him.
- Marshall - A thief who joins the protagonists.
- Samuel - Director of the Silivia Cognitive Science Center and a neuroscientist.
- Savannah - Girl that travels with the protagonists.
- Steven - Twin-brother of Melissa. Assistant in the Laboratory of the Unexplainable.
- Matthew Rockwell - Assistant at the Silivia Cognitive Science Center.
- Melissa - Twin-brother of Steven. Former squad member of the Silivian Militia.
- Nabi - An Alchemilia produced artificial tiefling. She is both a general and member of Alchemilia's bio-engineering department.
- Reti - Rebel Alchemilia general.
- Richard - The guardian and uncle of Melissa and Steven Devlin. Owner of the Laboratory of the Unexplainable.
- Tessa - Cicero's daughter. She helps to look for Xeren's soul. Her alias is "Beth Darwin."
- Warren - Silivian author.
- Wen Li - Owner of Plant Empire.
- Xeren - The God responsible for the creation of Euclid. Three hundred years prior to The Demon's Light, he was killed by the Powers.
- Xanvi - The leader of the Dream Eaters.
- Zade -A blind demon hunter who joins the Port City Eight in Headre.
- Aiola - A continent on Euclid.
- Eden - A planet originating from a parallel universe. It is the home of demons and angels.
- Euclid - The planet in which the events of The Demon's Light take place on. It was created by Xeren.
- Gladea - Small town in Thales. It is the location of one of Alchemilia Corporation's headquarters.
- Hala - A continent on Euclid. It has a large empire rulled by the queen, Ki'Yoki.
- Headre - A city in Muné occupied by skinwalker demons. They take on human forms to lure and kill travelers.
- Laboratory of the Unexplainable - A two-story building that researches the origin of demons and angels. It serves as the living quarters of Richard Smith and Steven Devlin.
- Muné - A continent on Euclid. It is the most wartorn continent.
- Nuyö - A continent on Euclid. It is known for its isolationist and atheist views.
- Port City - A seafaring city on the coast of Thales. It is most known for its proximity to Remnant Rock.
- Remnant Rock - An Alchemilia created artificial island. It is a military installation that appears similar to an oil rig.
- Silivia - The largest city on Euclid, and the human capital. Demons are unable to enter.
- Silivia Cognitive Science Center - A three-story building that operates as a neuroscience research facility.
- Thales - A continent on Euclid. It is known for being the location of the human capital, Silivia.
- Allucinor - Device capable of linking dreams between multiple people. Developed by Samuel Brownlee.
- Xeren's soul - Soul of the slain deity Xeren that orbits Euclid's atmosphere.
- Angels - An intelligent and strong humanoid species, capable of flight due to their wings, originating from the world Eden. They appear as androgynous humans.
- Demons - Beastly species that originate from Eden. Unlike angels, they posses a wide variety of experiences.
- Humans - Sapient species native to Euclid. They were created by Xeren.
- Alchemilia Corporation - A billion dollar corporation owned by Gabriel Arsene.
- Dream Eaters- An organization of inter-dimensional terrorists.
- Powers - A group of beings that can manipulate reality.
- Nuyö-Dyavol Coalition - An organization composed of multiple governments and the demon army.
- Alexander: A class of reality-altering entity. Alexander-class reality manipulators are capable of making drastic changes to the universe at will. Most Alexander-class entities are Powers.
- Aegis: A class of reality altering entity. Aegis-class reality manipulators are capable of controlling a substance known as Aether. By default, demigods are Aegis-class entities.
- Oneirois: A class of reality-altering entity. Oneirois-class reality manipulators interdimensional travel and manipulating the dreams of other creatures. Many Oneirois-class entities are Dream Eaters.