Dirk Slipstream

Dirk Slipstream was a criminal who served time in Volag-Noc after being caught by the Doctor.

Biography
Dirk was sentenced to one hundred years per person he killed during a jewel heist- seven hundred dead working out to about seventy thousand years. He escaped and went searching for the Mymon Key, an object of unlimited power, on the planet Gyre. Slipstream was presumably killed by carnivorous Sollogs while making one last desperate bid for the Mymon Key. (PROSE: Night of the Humans)

Behind the scenes

 * Precisely what body the Doctor was in when he last caught Slipstream was never specified. The Eleventh Doctor reflected that it had been 'years and regenerations' since he'd last seen Slipstream, but given Slipstream's knowledge of the Time War, the Eighth or Ninth Doctors seem the most likely candidates.