Greston Paltraki

 was the captain of a ship under the authority of the Congress of the Nine Planets. His home planet was Stebble.

Paltraki was found, alone, on his ship by the Thirteenth Doctor, Yaz, Ryan and Graham. Because he had been exposed to the psychotropic waves on the planet Ranskoor Av Kolos, Paltraki couldn't even remember his name. (TV: The Battle of Ranskoor Av Kolos)