Commanding officer

Commanding Officers are a role filled by officers that are in command of a particular duty, such as commanding a UNSC starship or leading a marine division. Before a Naval officer is given control of a starship, they usually are given the rank of Captain before such control is given. However, there have been known Navy COs that held the rank of commander. Marine COs are issued orders by the usually higher ranking Naval COs if on-board a starship. Marine Battalion COs are usually Majors or Captains. Marine Platoon COs are usually Lieutenants.

Known Navy Commanding Officers

 * Jacob Keyes (Captain)
 * Danforth Whitcomb (Vice Admiral)
 * Miranda Keyes (Commander)
 * Fleet Admiral Harper
 * Lieutenant Commander Jilan al-Cygni

Known Marine/Army Commanding Officers

 * Antonio Silva (Major)
 * Melissa McKay (Lieutenant)
 * James Ackerson (Colonel)