Mark Gregory was a researcher for International Electromatics. (PROSE: The Invasion)
He assisted in developing the Cerebration Mentor for use as a weapon against the Cybermen. After UNIT rescued Professor Watkins, Tobias Vaughn had him executed by the Cybermen. (TV: The Invasion) His body was recovered by C19 and kept in frozen storage within the Vault. (PROSE: The Scales of Injustice)