Jack Harkness

Biography
Jack Harkness worked as a Time Agent until he discovered that the Agency had erased two years of his memory. After leaving the agency, he worked as a conman, finding pieces of space junk and directing them to soon-to-be disaster sites, selling them to passers by, and letting them get destroyed before the buyers could pick up their merchandise.

While pulling one such con with a Chula Ambulance during the London Blitz he spotted Rose Tyler hanging from a barrage balloon. He rescued Rose, who introduced him to the Ninth Doctor. After sacrificing himself to help clean up after the damage done by the Chula Ambulance's nano-genes, he was rescued by the Doctor and Rose. He accompanied them on their subsequent adventures

Behind the Scenes
Jack Harkness' first name was originally "Jax".