Red Emperor

 was the 15th emperor of the Draconian Empire. In his youth played games of Sazou against the Doctor. On the Doctor's orders he isolated his planet from the rest of the Draconian Empire to protect it from the space plague. On his death he summoned the Doctor to stand vigil as a noble of Draconia. (AUDIO: Paper Cuts)

The Third Doctor later recalled his first meeting with the Red Emperor when he arrived on Draconia in 2540. (TV: Frontier in Space)

The Thirteenth Doctor referred to having been made nobility by the 15th Emperor, in order to win favour with a Draconian on late 19th century Earth. (PROSE: The Simple Things)