- You may be looking for Stewart Trask.
Trask was an arms smuggler and an agent of the Celestis.
During the Jacobite Rebellion in 1746, Trask was Willie Mackay's partner in smuggling weapons from France to Scotland, but he betrayed Mackay to the government army so he could seize control of his ship, the Annabelle. Trask became part of Grey's slave-trading ring, and took prisoners on board for transporting to Caribbean plantations. With the Second Doctor's help, the prisoners rose up against Trask and threw him overboard. (TV: The Highlanders)
While he was alive, Trask chose to become a Celestis agent, and when he died due to the Doctor's actions, the Celestis thought it would be appropriate to reincorporate him and send him as their representative to the East Indies ReVit Zone with the mission of recovering the Relic and carrying it back to Mictlan by whatever means necessary. When he arrived at the auction in the late 21st century, he had been dead for nearly four hundred years.
Due to her reconditioning in the Faction, Cousin Justine was irresistibly attracted to Trask. (PROSE: Alien Bodies) Godfather Morlock would later describe this as her "pathological attraction to dead things," though she insisted she had gotten over it. (AUDIO: The Eleven Day Empire)
Shortly before the auction, Mr Shift edited Trask's memory of his death in an attempt to turn him against the Doctor and distract him while the Shift secured the Relic. In the exaggerated memory, Trask remembered drowning, clawing at the water as something dragged him down by his ankles, and as he looked desperately up at the surface, he saw his killer's face, old and serious but full of infectious life. Trask recognised that life in the Eighth Doctor's face at the auction, and, when E-Kobalt tried to attack the Doctor, Trask tackled it, screaming, "He's mine, he's mine." He split his knuckles and fingers but successfully cracked the crystal with his undead strength.
Trask hid during the Krotons' attack on the ziggurat; he later approached the dying Mr Qixotl and put him into a mortal stasis to offer him recorporation in exchange for the Relic. Qixotl agreed to the offer, regaining his health, and Trask promptly took the Relic to Mictlan for recorporation. When the Eighth Doctor followed him, Trask gave him the Mark of Indenture, turning him into a Celestis servant, and gave him the now-worthless Relic to destroy. Trask did not realise that he had really Marked the Shift, who was trapped in the Doctor's mind. (PROSE: Alien Bodies)