The US Navy used to have a rank : Commodore. Discontinued sometime after WWII and, I heard, it caused some problems because it left a void between US military and other countries' military when the occasion called for officers of equal rank to meet and parlay.
Commodore ranked just above Captain and below "Admiral, lower half" (aka Rear Admiral) for staff officers.
So, how about countries other than US ... do you still have rank of Commodore?
I think the RAF has a rank air commodore between air group captain and air vice-marshall. Any others?