Who is Captain Jack Harkness, and how does he become a recurring character on the show?

Captain Jack Harkness is a fictional character in the British science fiction television series 'Doctor Who' and its spin-off series 'Torchwood.' He is portrayed by actor John Barrowman.

Jack Harkness first appears in the 2005 'Doctor Who' episode 'The Empty Child' and quickly becomes a fan favorite. He is a time traveler from the 51st century who becomes a recurring character in both 'Doctor Who' and 'Torchwood.'

Jack becomes the central character in 'Torchwood,' a spin-off series that follows the adventures of a team of investigators who deal with extraterrestrial threats. In 'Doctor Who,' Jack appears in several episodes across multiple seasons, including the show's 2005 and 2006 Christmas specials.

Overall, Jack's popularity with fans, along with his unique blend of humor, action, and drama, helped him become a beloved character in the 'Doctor Who' universe and a key figure in the 'Torchwood' series.

Captain Jack Harkness is a fictional character played by John Barrowman in Doctor Who and its spin-off series, Torchwood. The character first appears in the 2005 Doctor Who episode "The Empty Child" and subsequently features in the remaining episodes of the first series (2005) as a companion to the series' protagonist, the Doctor. Subsequent to this, Jack became the central character in the adult-themed Torchwood, which aired from 2006 to 2011.

Jack Harkness 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.

Jack joined the Time Agency, an organization that polices time travel, and became a Time Agent. 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.

In 1941, Jack met Rose Tyler, a companion of the Ninth Doctor. Jack and Rose became friends and allies, and they fought together against the Daleks. Jack was shot and killed by a Dalek, but Rose revived him using her newfound powers. However, Rose's powers accidentally turned Jack into an immortal being.

Jack became a recurring character in Doctor Who, and he appeared in several episodes of the series. He also appeared in the spin-off series Torchwood, which was set in Cardiff, Wales. Torchwood was a secret organization that investigated alien activity on Earth. Jack was the leader of Torchwood Three, the branch of Torchwood that was based in Cardiff.

Jack Harkness is a popular character in Doctor Who and Torchwood. He is known for his charm, wit, and his ability to regenerate. He is also a skilled fighter and a loyal friend.