Primus

Primus, The One and the Prime, was the immortal ruler of Mechanus and the modrons. He was godlike in power while in his realm.

"Quote? You desire a quote? The One and the Prime does not give 'quotes'."

- Primus to a record keeper of the Fraternity of Order

Abilities
Primus was considered a greater deity in Mechanus. His power over the modrons was absolute. All modrons obeyed the orders of Primus and carried out his plans. He was totally immune to all magic, and could issue telepathic commands to all modrons on Mechanus.

Society
Primus, although godlike, could be killed. Whenever slain, the highest-ranking secundus modron was promoted to his position and became the new Primus. In the modron society absolute law was committed by all modrons with the rare exception of a rogue.

History
Primus and his distinguished position among the modrons were known in the Realms at least since the discovery of the plane of Mechanus by Netherese archmage Lady Polaris around.

Primus was killed by Orcus during the demon lord's quest to become a deity. Even after being replaced by one of his secundi, the mind of the previous Primus remained present in the multiverse in the form of a vestige.