LGBT people have appeared on screen as long as there have been screens to appear on, but over the course of the last century the majority of these depictions have been negative. Historically depicted as something to be feared, those who did not conform to sexual or gender norms were often cast as villains or threats. From psycho-dykes to effeminate maniacs, their portrayal as LGBT automatically made them more threatening to an audience who already didn’t understand them. Due to the consistent depiction of LGBT people as villains, it became almost assumed that an LGBT person on film would always end up the villain. Think Mrs Danvers in Rebecca, Norman Bates in Psycho, Philip and Brandon in Rope.
Once homosexuality was decriminalised in the US, it would take a long time for Hollywood to catch up in its attitude toward them. Until the 1990s, it was very rare for a LGBT person to be portrayed in a positive light and even then, villains were their most common depictions. Think Buffalo Bill in Silence Of The Lambs, Catherine Trammell in Basic Instinct, Scar in The Lion King. But as Queer Cinema began to trickle into the mainstream, so too did more positive depictions of LGBT people.
The importance of television in the shift in attitude toward LGBT people on screen cannot be understated, however. While it took a while for an out gay character to appear on a primetime TV show, once they arrived, they arrived en masse. And due to the nature of television, in which characters are drip fed to their audience in their own homes, people became exposed to LGBT characters in a wholly different way. Through television, it became possible for the complexities of being LGBT issues were explored alongside other issues, subsequently becoming normalised and finally more human. Suddenly, LGBT people were not being portrayed as a threat and this trickled through into cinema too.