What is the title of the rank that corresponds to O-11 in the Navy?

The rank that corresponds to O-11 in the Navy is Fleet Admiral. This rank is the highest achievable officer rank in the U.S. Navy and is only awarded during times of war, as it is a five-star rank. The position of Fleet Admiral holds significant historical importance, having only been held by a select few individuals like William D. Leahy, Ernest King, Chester W. Nimitz, and William Halsey Jr. The title symbolizes a level of authority and responsibility that goes beyond that of a four-star Admiral (O-10), which is the highest peacetime rank, focusing on the command of fleet operations and strategic naval engagements.

Other ranks, such as Admiral (O-10), Vice Admiral (O-9), and Rear Admiral Upper Half (O-8), represent lower levels of authority and have different roles within the Navy hierarchy. Therefore, the Fleet Admiral designation specifically signifies the pinnacle of naval rank and distinguishes it from these other ranks.