The Fabricator-General, also known as the Magos Mechanicus, is the highest ranking position of the Adeptus Mechanicus. A Fabricator-General oversees his respective Forge World along with his deputy, the Fabricator-Locum.
While many Forge Worlds have their own Fabricator-General, it is the Fabricator-General of the Mechanicum homeworld of Mars that is the most powerful and prestigious. In addition to overseeing the general Mechanicum, the Fabricator-General of Mars is the head of the Cult Mechanicus and speaker of the Martian Parliament. The Fabricator-General of Mars is most often chosen from the Forge Master of the Olympus Mons Forge.
During the early days of the Great Crusade, the Mechanicum was led by the Martian Parliament. The Fabricator-General acted as the Martian ambassador to Terra and had a seat on the War Council of the Great Crusade. At some point before Kelbor-Hal held the position, the post had evolved into the leader of the Mechanicum.
At the end of the 41st Millennium the Fabricator-General was Oud Oudia Raskian, but his position is being threatened by Archmagos Belisarius Cawl, the famed creator of the Primaris Space Marines. Cawl has been pushing the recently resurrected Lord Commander Roboute Guilliman to make him Fabricator-General, but the Primarch distrusts Cawl and believes he borders the Heretekal.
- Kelbor-Hal: Fabricator-General of Mars who sided with the forces of Chaos during the Horus Heresy and founded the Dark Mechanicum
- Zagreus Kane: Succeeded Kelbor-Hal during the Schism of Mars as the highest-ranking Adept still loyal to the Imperium.
- Kubik: Fabricator-General of Mars during the War of the Beast
- Gastaph Hediatrix: Fabricator-General of Mars during the Age of Apostasy
- Uixot: Fabricator-General of Mars during the 8th Black Crusade
- Oud Oudia Raskian: Fabricator-General of Mars during the Thirteenth Black Crusade
- 1: Codex Imperialis, pg. 41
- 2: Codex: Sisters of Battle (2nd Edition), pg. 13
- 3: The Horus Heresy Book One - Betrayal, pg. 18
- 4: Mechanicum 3.04
- 5: Codex: Skitarii (7th Edition) pg.13
- 6: Dark Imperium (Novel) - The Cawl Inferior