The leader of an Imperial world is known as a Planetary Governor also an Imperial Commander, an individual with the (often hereditary) authority to rule a world in the Emperor's name.
Naturally, since the vast and dispersed nature of Imperial territory 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 (or she) is duty-bound to the Adeptus Terra. Essentially though, he is an independent governor. As long as the planet's tithes, mutant and psyker "head counts" are kept under control and the planet is governed competently, he is free to run the planet however he chooses.
They are expected to defend the planet in the name of Imperium, maintaining Planetary Defense Forces and orbital defences. Due to the fickle nature of the warp, 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 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 period of the Imperium this was a simple process, a straightforward pledge to provide a certain number of troops and to fight in person. This was 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 labour. This was later replaced with a tithe. 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 defense forces. The tithe is also a percentage of the planet's produce. Most tithes are regular obligations, while others are demanded when specific circumstances are met.
This leads to a close relationship between Planetary Governors and the Departmento Munitorum who look after the deployment of men and supplies across the galaxy. Both tithes go to the Munitorum, which can raise soldiers from across entire sectors.
Notable Planetary Governors
- Gerontius Helmawr of Necromunda
- Herman von Strab
- 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
- Lukas Alexander of Kronus.