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. Barrowman reprised the role for appearances in Doctor Who in its third, fourth, and twelfth series, as well as specials "The End of Time", and "Revolution of the Daleks".

John Scot Barrowman is a Scottish-American actor, author, presenter, singer and comic book writer. He is known for his roles as Captain Jack Harkness in Doctor Who and spin-off Torchwood, (2006–11) and as Malcolm Merlyn in the Arrowverse (2012–19).