Dalek Puppet Emperors were a type of Dalek leader. During the time leading up to the Last Great Time War, a Puppet Emperor openly declared his hostility to the Time Lords of Gallifrey. (PROSE: Meet the Doctor)
Behind the scenes
Meet the Doctor does not identify the specific puppet emperor who declared hostilities, but, in Remembrance of the Daleks, Davros, who had dubbed himself the Emperor of the Daleks, did so.