Supreme commander
Supreme commander was a title given to the commander in chief of a government's military forces. 

The Chancellor of the Klingon Empire also bore the title of Klingon Supreme Commander. When Chancellor K'mpec requested that Jean-Luc Picard mediate the contenders for his replacement as Chancellor, and Picard respectfully declined, K'mpec told him that such a refusal to the dying request of the Klingon Supreme Commander would be an insult by the Federation to all Klingons. ()

The title was utilized in the Federation Alliance during the Dominion War. On Benjamin Sisko's recommendation, Martok was made Supreme Commander of the Ninth Fleet in 2374, following Operation Return. Martok resented the position because of all the paperwork and bureaucracy involved in commanding an entire fleet. ()

Supreme Commander was also the title given to Quark by Nog when they were being interrogated by Earth United States Army Air Forces  Wainwright in 1947. ()

nl:Oppercommandant
Titles