Jack was born in the 51st century. He was brought up around the year 5000 on the Boeshane Peninsula, a sandy beach area. He lived with his mother, father and younger brother Gray.
Later on in life Jack worked as a Time Agent, during this time he worked with John Hart another Time Agent. When Jack left the Time Agency he became a con-man, it was during this time that he travelled to 1941 and took the name of Captain Jack Harkness, a deceased American. Jacks real name is unknown.
Whilst pulling a con with a Chula ambulance during the London Blitz he met the Doctor and Rose thinking they were Time Agents. Jack became part of the TARDIS crew and travelled with the Doctor for a while until they arrived on Satellite 5 in the year 200,100 AD during a Dalek invasion. Jack was shot by a Dalek and then brought back to life by Rose, Rose couldn’t control what she was doing so she brought him back to life forever, Jack is now immortal. The Doctor wasn’t comfortable with what had happened so he ran from the scene leaving Jack behind on Satellite 5.
Jack still had his vortex manipulator from the Time Agency, he used it to travel back to Cardiff as he knew the Doctor would eventually stop there to refuel the TARDIS using the rift. Jack was unable to control the date so ended up in the year 1869.
Two Torchwood agents learnt of Jacks immortality and heard him mentioning the Doctor so they captured him. They tortured him hoping to find out why he couldn’t die and how he knew the Doctor. Eventually Torchwood offered Jack his freedom as long as he worked for Torchwood.
On New Year’s Day 2000 one of Jacks colleagues suffered a nervous breakdown and killed all the staff at Torchwood three. Jack spent the next few years rebuilding Torchwood and recruiting new members.
In 2008 Jack found the TARDIS and travelled to the end of the universe with the Doctor and Martha. Jack helped the Doctor and Martha defeat the Master, the Doctor asked Jack to rejoin the TARDIS crew but he chose the stay at Torchwood.
The Daleks moved the Earth to the Medusa Cascade, former Prime Minister Harriet Jones contacted Torchwood and other friends and companions of the Doctor via the Sub-Wave Network. All the alien technology combined was enough the contact the Doctor.
In 2009 the Government destroyed Torchwood three hoping to kill Jack as he was one of the few people that knew of the 456 alien threat. After losing Torchwood three, Ianto and his grandson Jack decided to leave Earth. Jack was last seen on an alien bar where the 10th Doctor visited him briefly.