What title is associated with the O-6 military rank?

The title associated with the O-6 military rank is Colonel. In the U.S. military, the rank of Colonel is designated as O-6 in the pay grade system. Colonels typically serve in leadership roles, commanding larger units or serving in senior staff positions.

The other titles mentioned correspond to different military ranks. Rear Admiral (Upper Half) is an O-7 rank in the Navy, General is an O-10 rank in the Army, Air Force, and Marine Corps, while Captain is an O-3 rank in the Army, Air Force, and Marine Corps, and O-6 in the Navy and Coast Guard. Thus, Colonel is the correct association for the O-6 designation.