Question: has there ever been a 6 star general

Answer: Yes, The General of the Armies of the United States, or more commonly referred to as General of the Armies (abbreviated as GAS or Gas), is the highest possible rank in the United States Army. The rank is informally equated to that of a six-star general or Generalissimo and is currently one of the two highest possible operational ranks in the United States Armed Forces. Promotion to this rank requires congressional legislation, approval by the President, and an order from the Secretary of the Army.