The Marine Corps commonly calls its senior NCOs, "______________".

The correct term used to refer to senior Non-Commissioned Officers (NCOs) within the Marine Corps is "Staff NCOs." This designation is important within the structure of the Marine Corps as it signifies the rank and responsibilities held by these NCOs. Typically, Staff NCOs in the Marine Corps include ranks such as Staff Sergeant, Gunnery Sergeant, Master Sergeant, and First Sergeant, each of which carries specific leadership responsibilities and expectations.

Using the term "Staff NCOs" emphasizes their role as experienced leaders who have transitioned beyond basic NCO positions to take on more significant mentorship and command responsibilities within units. This distinguishes them from lower-ranking NCOs who might not possess the same level of experience or authority.

The other terms mentioned do not accurately represent the classification of Marine Corps senior NCOs. "Chiefs" is often associated with the Navy and its Chief Petty Officers. "Senior Officers" usually refers to commissioned officers at higher ranks and does not apply to enlisted NCOs. "Commanders" refers to officers in charge of units and does not encompass the NCO ranks or their specific role within the Marine Corps hierarchy.