The Central Galactic Marine Corps is a branch of the Armed Forces of the Central Galactic Union responsible for providing power projection and quick reaction against immediate threats on land, at sea, in the air, and in space, using the mobility provided by both the Navy and Spacy to swiftly deliver combined-arms task forces in any environment. It is administered under the Department of the Navy within the Ministry of War, but is considered a separate branch of armed uniformed service to the Republic, and operates space combat elements as well as air-ground task forces. The current Chair of the Joint Military Staff, the highest-ranked professional military officer, is a Marine Corps marshal.

The Marine Corps has a storied history with roots in the naval infantry branches of various Earth militaries, in particular the UN Marines, the United States Marine Corps, the Royal Marines, and the Russian Naval Infantry. Its direct predecessors are the space-borne and seaborne infantry forces of the Terran Empire and its allies, especially the Terran Imperial Navy Marine Corps.

The Marines are the première force employed by the Union military for amphibious warfare, orbital drops, and orbital combat operations. The Marines operate ground forces and tactical aviation units from sea-going vessels, transport spacecraft, and orbital stations, providing rapid response to emerging threats on provincial and colony worlds, and "tip of the spear" shock forces in expeditionary warfare.

The Marine strategic structure is framed around Fleet Marine Forces, a combined force of all Marine units stationed in a particular astrographic area. A Fleet Marine Force is composed of around six to eight Marine Field Forces. A Field Force is composed of eight to ten Marine Armies. A Marine Army is composed of six to ten Marine Expeditionary Forces. A MEF is an operational unit of 44,000 soldiers.

Community content is available under CC-BY-SA unless otherwise noted.