The leader of an Imperial world is known as a Planetary Governor or sometimes as an Imperial Governor, and is considered an Imperial Commander in military matters. Regardless of his or her title, a Planetary Governor is an individual with the (often hereditary) authority to rule a world or even an entire star system in the Emperor's name. The Planetary Governor of a particularly important world, may also serve as a sub-sector, Sector or even Segmentum Governor in some cases. Naturally, since the vast and dispersed nature of Imperial space would make a totally centralised system of government unfeasible, the Planetary Governor is given discretionary control over the administration (including governance, defence and development) of the planet in question. In theory he is duty-bound to the Adeptus Terra. Essentially though, he is an independent governor who can rule his planet as he sees fit with only minimal interference from the Imperium. As long as the planet's Imperial taxes are paid, its mutant and psyker populations are kept under control, the requisite tithes of psykers and Imperial Guard regiments are delivered to the Imperium and the planet is governed competently, the Governor is free to run the planet however he chooses.
Imperial planetary governors are expected to defend the planet in the name of Imperium, maintaining the necessary Planetary Defence Forces and orbital defences. Due to the fickle nature of the Warp, astropathic communication with the Adeptus Terra is often delayed and sometimes prevented entirely. Often this means that Governors must make decisions on the defence of their world without advice and help from Terra, meaning that for the world to prosper, every Governor must be adept at military matters as well as the development of the planet's trade infrastructure.
Planetary Governors are usually referred to in Imperial feudal nomenclature as "Lords", and their position often becomes hereditary.
Even though Governors are given these powers over a planet, they come at a price. The Governor is a sworn vassal of the Imperium, and as such is required to provide military support to local campaigns. In the early history of the Imperium this was a simple process, a straightforward pledge to provide a certain number of troops and to fight in person when required. This was later seen to be too inflexible because as the Imperium grew, the differing numbers of troops provided made poor use of some planets' populations and on others too high a proportion of the population was sent to war, leaving the planet sorely short of the labour required to efficiently run its economy. This pledge was thus later replaced with a tithe to provide Imperial Guard regiments. It is assessed by the wealth and available resources of the planet.
As part of the tithe, the governor is expected to supply troops to the Imperial Guard, the troops often being requisitioned from the planet's existing planetary defense forces. The tithe is also a percentage of the planet's economic output, in whatever form that may be derived. Most tithes are regular obligations, while others are demanded when specific circumstances are met.
These requirements lead to a close relationship between Imperial Planetary Governors and the officials of the Departmento Munitorum who look after the deployment of men and supplies across the galaxy. Both military and economic tithes go to the Departmento Munitorum who can raise soldiers from across entire sectors of the galaxy.
Notable Planetary Governors
- Gerontius Helmawr of Necromunda
- Herman von Strab of Armageddon
- Lufgt Huron, former "Tyrant of Badab"
- Marius Hax, Sector Governor of Calixis and Planetary Governor of Scintilla
- Xian Torus of "the World that died in One Night"
- Mykola Shonai, of Pavonis
- Codex: Imperial Guard (3rd Edition, 2nd Codex)
- Codex: Armageddon (3rd Edition)
- Codex Imperialis
- Warhammer 40,000: Rogue Trader
- Nightbringer by Graham McNeill