Fictional character in the TV series Doctor Who and Torchwood
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.
https://en.wikipedia.org/wiki/Jack_Harkness