There are two other known ranks of Princeps, other than the basic. They are:
- Princeps Majoris is a rank given to those who control entire battle groups of Titans, the equivalent of being a squad leader.
- Princeps Senioris is the leader of a Titan Legio. He is the master of all of that Legio's Titans.
A Princeps is trained at the Collegia Titanica. Unlike most of the Adeptus Mechanicus personnel, Princeps recruits are not only selected from the Forge Worlds' own civilians, but from anywhere the Mechanicus may find suitable candidates. This is because only the strongest of will can sustain a mind-link with the Titan's powerful spirit with their sanity intact, and the rarity of such specimens requires a larger selection pool.
- Warhammer 40,000 4th Edition Rulebook, Adeptus Mechanicus