Padishah Emperor was the titled assumed by the head of House Corrino, who was also ruler of the Fifth Imperium. He was always male and human. The Landsraad, however, did decide which male noble of the Corrino family would be elected by a Landsraad majority, meaning the Padishah Emperor was a type of Elected Monarch.
The Padishah Emperor could only be removed by the Landsraad for serious crimes. In case he was underaged or physically or mentally incapacitated, the Landsraad selected an Executive Council with regency powers.