Captain Jack Harkness, played by John Barrowman, is a character from Doctor Who and one of the stars of the spin-off series, Torchwood. He first appears in the 2005 Doctor Who episode "The Empty Child" and spends the remainder of the season as a companion to the Doctor. He was the first openly queer character to appear in the history of Doctor Who.
In 2006, the spin-off series Torchwood launched, with Captain Jack as a main character. Between being immortal and saving the world, he also finds the time to be a fun-loving, flirtatious hero who carries on many relationships.
One of his biggest love stories in the Torchwood series is between Jack and Ianto Jones. It starts out as flirtation and a fling, but over time it becomes obvious that Ianto makes Jack more empathetic, kind, and considerate. Ianto is one of the very few people Jack is willing to put ahead of himself. In the 2009 episode "Children of Earth", Ianto is suddenly killed, and Jack spends time crippled by his grief.
He also has ongoing sexual tension and flirtation running with another member of the Torchwood team, Gwen. Throughout the show, ex-lovers and current lovers show up, and Jack is very open about his attraction to men and women. There is no coming out drama, self-doubt, or bi erasure. He is just happily bi.