Torchwood is a more adult spin-off of the long-running Doctor Who series. I'm fairly certain all of the main characters from the show are queer. Russell Davies, the creator of the show, was intentionally trying to break the idea of sexuality being fixed or stable. While the relationship between the characters Jack Harkness and Ianto Jones develops through the series, we learn about their past relationships with men, women, and aliens as well. There is an episode where Toshiko Sato is in a relationship with an alien who takes the female form, but later in the series, she attempts to create a relationship with another main character, Owen Harper.
While this show celebrates the fluidity of sexuality, it is also problematic. The three male characters, Jack, Ianto, and Owen, are fluid in their sexualities, but there is no fluidity in their gender. They are stereotypical “manly” men who are violent, aggressive, and in charge. They show few emotions other than anger. They are able-bodied and white. Toshiko is a problematic character because of how she's portrayed, stereotypically asian and feminine. She's portrayed as passive, overly academic, strait-laced, and unobtrusive. Gwen Cooper is complex character. She demonstrates her sexual fluidity, but for most of the series, she's one half of a typical heterosexual couple. While she has a more apparently masculine, aggressive role (she's always seen kicking alien butt where as he is usually seen in their home), she's also the one who ends up pregnant (once with an alien baby and once with an actual human baby she wanted).