|First black and white kiss on US television, Kirk and Ohura|
It's worth noting that George Takai wanted gays in the original Star Trek, but Gene Roddenberry was against it as it would likely have meant the end of the show. Even the first kiss on TV between a black and white person was highly controversial in the US, and I think from memory that episode wasn't aired in some southern US states. The groundbreaking kiss was between Kirk and Ohura.
Watch the announcement about Discovery below.