In Utopia , it is revealed the Doctor did n't want to bring Jack Harkness .
During his time with the Doctor , Jack matures into a hero , and in his final 2005 appearance , he sacrifices himself fighting the evil alien Daleks ; Rose brings him back to life while suffused with the power of the time vortex , but when the power leaves her she does n't remember doing it , so she and the Doctor unwittingly leave him behind on Satellite 5.Harkness returned in 2006 as a character of the spin-off series Torchwood , in which he is a member of the Cardiff-based Torchwood Three in combating alien threats and monitoring a spacetime rift which runs through Cardiff .
Jack Harkness