|Master Chief Petty Officer|
Master Chief Petty Officer
Master Chief Petty Officer Rank Insignia
Master Chief Petty Officer is the most senior grade of Chief Petty Officer, and is the highest non-commissioned officer grade in in Starfleet. In comparison to infantry ranking systems, this rate is approximately equivalent to the most senior Sergeant grade, such as Sergeant-Major. Personnel of this grade could be addressed simply as "Chief" (or more properly, "Master Chief"), and sometimes by their job title, such as "Master Chief Specialist."
While nominally subordinate to all commissioned officers, Master Chiefs wield far more influence and authority than most junior officers and act as mentors and advisors to senior officers. Master Chiefs have decades of practical experience and are an indispensable source of technical skill and leadership on Starfleet vessels.