Modrons

Modrons are extraplanar automatons haling from the Empyreal Universe plane of existence known as Clockwork Nirvana of Mechanus, or just Mechanus for short. They are created by, and extensions of, the divine being called Primus. Modrons are beings of absolute law that adhere to a hive-like hierarchy, their existence a clockwork routine of perfect order.

Absolute Law and Order

Under the direction of Primus, modrons increase order in the multiverse in accordance with laws beyond the comprehension of mortal minds. Their own minds are networked in a hierarchal pyramid, in which each modron receives commands from superiors and delegates orders to underlings. A modron carries out commands with total obedience, utmost efficiency, and an absence of morality or ego.
Modrons have no sense of self beyond what is necessary to fulfill their duties. They exist as a unified collective, divided by ranks, yet they always refer to themselves collectively. To a modron, there is no "I," but only "we" or "us."

Absolute Hierarchy

Modrons communicate only with their own rank and the ranks immediately above and below them. Modrons more than one rank away are either too advanced or too simple to understand.

Cogs of the Great Machine

If a modron is destroyed, its remains disintegrate. A replacement from the next lowest rank then transforms in a flash of light, gaining the physical form of its new rank. The promoted modron is replaced by one of its underlings in the same manner, all the way to the lowest levels of the hierarchy. There, a new modron is created by Primus, with a steady stream of monodrones leaving the Great Modron Cathedral on Mechanus as a result.

Drones and Hierarchs

The modron race is divided in two large categories; the Drones (sometimes called base modrons) and the Hierarchs.

Drones

Drones are the most numerous and most simple of the modrons. While all modrons are a combination of organic empyreal matter and machinery, the drones are decidedly more machine and approximate (mostly simple) geometric shapes. Drones are divided in specific ranks that also define their shape and appearance.
From least to greatest they are: monodrones, duodrones, tridrones, quadrones, and pentadrones.

Hierarchs

Hierarch Modrons are the officers and commanders of the modron race. Unlike drones, the more higher up the hierarchy they are, the less machine-like they appear, with the four Secundi that are highest in the ladder looking decidedly humanoid.
The hierarch subtypes are: decatons, nonatons, octons, septons, hextons, quintons, quartons, tertians, secundi.

The One and the Prime

Of course, at the very top of the hierarchy is Primus himself.

Rogue Modrons

A modron unit sometimes becomes defective, either through natural decay or exposure to chaotic forces. Rogue modrons don't act in accordance with Primus's wishes and directives, breaking laws, disobeying orders, and even engaging in violence. Other modrons hunt down such rogues.

The Great Modron March

When the gears of Mechanus complete seventeen cycles once every 289 years, Primus sends a vast army of modrons across the multiverse, ostensibly on a reconnaissance mission. The march is long and dangerous, and only a small number of modrons returns to Mechanus.

Origin/Ancestry

Extraplanar Entities hailing from Mechanus