Archon (from the Greek archai, "origins" or "to rule"), a word which in real-life is a term for an autocratic ruler and a type of hostile angel-like beings from the religious movement Gnosticism. In relation to /tg/ interests, it is a name used to describe several characters in a series of games within the various hobbies of /tg/. It is also an old digital board game.
The most commonly known type of Archon, the Celestial Archons live mostly in the Seven Mounting Heavens of Celestia. They form a hierarchy of virtue: the less enlightened stand under the guidance of the more enlightened. This goes all the way from the simple Lantern archons (glowing balls of light about a foot across who try to inspire others to live in virtue and do good) all the way to the Celestial Hebdomad, the council of seven archangels who lord over the people of Celestia. While the hierarchy mirrors the ranks of the Baatezu in hell, the Archons have no rivalry between themselves: if anything helping your equals promote at the cost of you not being able to work on your own promotion is considered to be a good and noble thing (and you'll see this on your own evaluation).
Introduced in Points of Light, the Elemental Archons were the soldiers in the armies of the Primordials. They are more than just elementals: what others lack in regards to self-awareness and initiative the Archons do have. While being highly militaristic and strictly adhere to their superiors they are almost always Chaotic Evil because they want to return the world to its shapeless and fluctuating form prior to the arrival of the gods. They of course do not like this, which was the entire reason the Primordial War even started.
After the gods defeated the Primordials the Archons fell to the service of various elemental lords, both petty and great. They still retain their desire to return their masters to their rightful place in the world and would potentially betray everyone they work for to see this done.
Archons exist out of one element (fire, ice, earth, water, lightning etc.) like normal elementals do, but instead they wear armor over parts of their body. They almost always armor their torsos, shoulders and heads, though the exact nature of the armor varies per type. They are human-sized, with everything above the waist being the same shape as humans but instead are made out of one element. Some of them wield weapons made in the style that fits the Archons, but some use weapons made out of fire, ice and so on. If an Archon would be slain it dissipates, possibly alongside its weapon(s) and leaves behind its armor: while a PC can wear it its light contsturction makes sure it does not offer a lot of protection.
5e renamed the Elemental Archons to Elemental Myrmidons instead.
|The inhabitants of the Planes of Planescape|
|Upper Planes:||Aasimon - Angels - Animal Lords - Archons - Asuras - Eladrin - Guardinals - Lillend|
|Middle Planes:||Formians - Githzerai - Inevitables - Marut - Modrons - Rilmani - Slaadi|
|Lower Planes:|| Alu-Fiends - Baatezu - Bladelings - Cambions - Demodands - Erinyes - Hags |
Hordlings - Imps - Kytons - Marilith - Succubi - Tanar'ri - Yugoloth
|Transitive Planes:||Astral Dreadnought - Githyanki|
|Inner Planes:||Azers - Elementals - Genies - Grues - Mephit - Salamanders - Sylphs|
|Sigil:||Dabus - Cranium Rats|
|High-ups:||Archangels - Archdevils - Archfey - Archomentals - Demon Princes|