As a large majority of Messiah's political scene is driven by the noble houses, essentially it replaces a faction system with a house-based one. All groups and organizations established in board canon are essentially extensions of a house. Houses may be highborn, lowborn, or somewhere in-between, and most can and often will serve below a higher house as a vassal line.

Major houses in Dalmasca and Jihon cannot be made at this time. Minor vassal houses are, however, always free to be made. Galace and the Free Cities that have nobility can have player-made major houses in them. Macenia does not have noble houses.
House names with a bullet beside them are minor vassals of the first house name lacking a bullet above them.

Dalmasca

Asheron
Cassimer

Essair

Greyson
Lancaster

Jihon

Kanesuke
Munemoro
Tachibana
Tran
Zhu

Haradi

Assad

Saqqara

Lucain

Fallen Houses

Kenleigh