The Commander is a Career from the Age of Rebellion Core Rulebook.
Individual warriors can act bravely and with resolute determination, accomplishing great things. They can also cause untold havoc without any real achievement, save property dmage and loss of life, including their own. A motley mob of people capable of violence is only a threat until a more disciplined force arrives to put it down. That is where the Commander comes in, organizing, managing, and leading fighters and other people who serve in a military force so they accomplish truly great things together. They must see the bigger picture, make the hard decisions, and motivate their people to charge into the jaws of death for a greater cause, all while never wasting personnel or resources. Without good commanders, true victory is impossible for any military.
Captain Rex, General Dadonna, and General Madine are all examples of Commanders in Star Wars.