The title of Emperor on Barrayar passed preferentially in the male line. Although two known emperors, Dorca Vorbarra and Ezar Vorbarra, succeeded to the throne, both were collateral descendants of House Vorbarra with close ties to the prior emperor. In Dorca's case this was through his mother, and in Ezar's case through his wife, who was Yuri Vorbarra's sister.
In the case of an Emperor succeeding in his minority, a Regent of Barrayar was appointed. The Regent needed to be confirmed by the Council of Counts and the Council of Ministers, and held power until the Emperor reached his twentieth birthday, although the young Emperor retained all ceremonial duties. Before Aral Vorkosigan's Regency, there had not been a regent for 120 years.
The Emperor was also a District Count in his own right, and the capital city of Vorbarr Sultana was part of his district. After the annexation of Sergyar, it also became a personal possession of the Emperor.
Emperors of Barrayar included:
- Xian Vorbarra 
- Vlad Vorbarra le Savante
- Dorca Vorbarra the Just
- Yuri Vorbarra ("Mad Yuri")
- Ezar Vorbarra
- Gregor Vorbarra
Pretenders to the Imperium included:
The title of Emperor brought with it not only governmental responsibility, but also the duty of acting as an interface between the haut project and the rest of the Empire. As part of his genetic role, the Emperor chose haut-women to be his Empresses. Each of these Imperial Mothers designed one son for the Emperor, and was forbidden from having other children unless the Emperor chose to have another son by her. The Emperor designated his heir at his own choice from among the prince-candidates, although civil war usually followed an Emperor's death as prince-candidates warred among themselves. Fletchir Giaja had four Empresses, including Rian Degtiar.
The Emperor of Cetaganda held the title of Celestial Lord and was referred to as "my Celestial master" by individuals in his direct service. His mother (or after her death the mother of the Imperial heir) was the Celestial Lady.
Notes and references
- Barrayar chapter 1
- The Vor Game chapters 1,3,4
- Memory chapters 16,20
- The Warrior's Apprentice chapter 19
- Mirror Dance chapter 13
- A Civil Campaign chapters 2,16
- Shards of Honor
- Barrayar chapter 19
- Cetaganda chapters 4,16
- The Warrior's Apprentice chapters 15-17
- A Civil Campaign chapter 4