Each of the three branches of the Military (Navy, Marines, Army) has its own representative, called Legatus, who are often considered (presumably with accompanying staff) the High Command of that Branch of service.
"When Messer consolidated his power and transformed from the Prime Citizen to the Imperator, he also bonded the powers of the High-General to the position of Imperator (in an effort to prevent any other faction of the government from legally wielding the military against him). Therefore, the UEE High Command was created, a committee of representatives from the branches of the military to facilitate the orders of the Imperator. Think of it like the Joint Chiefs, a consolidation of high-ranking military officials who organize and brief the Imperator about military matters."
Star Citizen Writer's Guide - Part Two
At current, the position of Legatus Navium is held by Lavinia Wallingford. The Legatus Exercitus' surname is Cobol.
- Legatus Navium - Naval High Command
- Legatus Marinuum - Marine High Command
- Legatus Exercitus - Army High Command