What is the rarest e9 rank in marine corps?

In the United States Marine Corps, the rarest E9 rank is Master Gunnery Sergeant (E9). This rank is the highest enlisted rank in the Marine Corps and is only achieved by a small percentage of enlisted Marines who have demonstrated exceptional leadership, expertise, and experience in their military career. Master Gunnery Sergeants typically serve in specialized roles and are considered subject matter experts in their field.