Master of the Keep

The Master of the Keep is a Space Marine Master and is the Space Marine Captain who has been designated to serve as the Chapter Master's second-in-command.

The Master of the Keep will also serve as the regent of the Chapter homeworld in those cases where the Chapter Master is off-world or has been incapacitated.

The title is usually borne by the commander of the elite 1st Company in Codex Astartes-compliant Chapters.