Master Chief Petty Officer

Master Chief Petty Officer, abbreviated to MCPO, also nicknamed as "Top Chief" out of respect for John-117, is the highest enlisted rank in the United Nations Space Command Naval Command (NAVCOM) rank structure; including the UNSC Navy and Office of Naval Intelligence. It is preceded by Senior Chief Petty Officer.

Responsibilities
Master Chief Petty Officers are often Fleet administration or HIGHCOM staff. They can also lead companies with Captains and Lieutenants that outrank them.

Insignia
The metal insignia has three chevrons capped by a rocker. The UNSC eagle is placed on top of the rocker, with the eagles wingtips having stars at the end of them.

Ceremony
Master Chief Petty Officers are often given an ceremony on the largest ship in a fleet.