The Could've Been King led the Army of Meanwhiles and Neverweres during the Last Great Time War. He was described by the Doctor as one of the potential horrors that would be released when the Master broke the time-lock on the war, along with the Nightmare Child and the Hordes of Travesty. (DW: The End of Time)
- Beyond this mention, there is no further description of the Could've Been King or his army.