What rank is indicated by a single gold bar collar device in the Marine Corps?

The rank indicated by a single gold bar collar device in the Marine Corps is Second Lieutenant. This insignia symbolizes the entry-level officer rank in the Marine Corps, which is the starting point for all commissioned officers. The single gold bar designates the officer's position within the hierarchy, signaling their initial responsibilities and leadership role within the Marine Corps structure.

In contrast, the other ranks listed, such as Lieutenant Colonel, Major, and Captain, are represented by multiple insignias, which reflect higher levels of experience and authority in the officer ranks. Thus, recognizing the significance of the single gold bar is essential for understanding rank identification within the Marine Corps.