Highest active-combat rank Delta Force?

I know very little about SAS and this is therefore directed mainly concerning SFOD (Delta). You cannot try out for SFOD unless you are at least an E-5 (Sergeant) in the Army. The most common rank for operators in SFOD is E-7 (Sergeant First Cl). SFOD is NCO led and therefore there are not many opportunities for Officers to play within the rank. Usually the Officer side of the house is within the Operations side and of course as the Commander. The highest rank within SFOD would be the Commanding Officer which is an O-6 (Colonel) billet but he is NOT an operator.