Alright, so the Nine are confusing as hell from our findings. Their Grimoire card has nine passages detailing individuals and groups of people. We are currently trying to figure out who they are, but we have some ideas. They are from all over, and not all are seemingly "alive". Ghosts and Warminds are cited as being a part of the Nine. I don't know if they were present during the Collapse, at least not openly. I'm actually willing to bet that they came after the Traveler went to sleep due to some of the individuals/groups that seemingly make up part of the Nine. Literally, no one at the Tower knows if anyone lets Xur sell his goods or how he even gets there. There are rumours that it could be either the Speaker or the Vanguard who have a part in that, but he's a mysterious being. My guess is that he acts on behalf of the Nine and comes at their pleasure rather than ours. In the end, I don't think we've been properly introduced to any of the Nine. Only time will fully tell who they are, either by their coming to light or us figuring out who they are.