Zachary Cross Flane

Zachary "Zack" Cross Flane was second-in-command of Sanctuary Base 6. He took charge after the death of Captain Walker when their ship crashed on the planet Krop Tor after encountering the black hole which the planet was orbiting. Not really wanting the command, he nevertheless successfully dealt with the attack by The Beast and took the survivors away in a shuttle ship. Presumbably, after the Doctor and Rose saved him, he then returned to Earth. (DW: The Impossible Planet/ The Satan Pit)

Other information
His mention of the Torchwood Archives suggests very strongly that he worked for a future version of the Torchwood Institute, though we do not know if his the other crew members of Sanctuary Base 6 also worked for Torchwood.