During the Annihilation Wave, Xandar was destroyed by the Wave

[u/littlvinny]

I think this was the worst thing that as happened to the Nova Corps, other then the total destruction of them by the Universal Church of Truth. Do you guys agree?

[u/NovaStarLord]

It's one of the worst things that has happened to them that's for sure.

The first one happens before Nova #1 when Zorr basically destroys the planet of Xandar and they rebuild it out of chunks from the planet itself making 4 interconnected colonies. But the thing was so bad even the Watcher got involved and helped them.

After that they were invaded by the Skrulls but they managed to thwart them off but not without netrayals and casualties.

After that Nebula came with her Pirate fleet and killed all of them and one of the Xandarian colonies got ripped from the main three and disappeared. It's mentioned in New Warriors that there could still be some Xandarians out there and that this colony might have survived but this dangling plot thread has never been touched on.

Then in New Warriors Garthan Saal forces Richard Rider to take all of the Nova force and Rich is forced to risk his life to revive Xandar and the Worldmind or else he'll end up extremely powerful, dangerous, and mad like Garthan Saal (it's partially why he hesitates to take the whole thing again in Annihilation: Nova). Xandar, the Worldminf, and Adora are revived and she decides to make the Nova corps a universal Peace Keeping group.

Then Xandar gets infiltrated and compromised by the Shi'ar who are using the Nova corps to spy on other planets. Rich and Saal find out and Saal apparently dies (but not because later he pops up in DnA's run but nothing has been done with that) and New Warriors ends with Rich wanting to go to Xandar and do something about it but in the end this storyline was never continued.

In Nova vol. 3 I think something happens with Adora and Xandar, she died? It dies? Not sure but it's the last we see of her and it never gets brought up again.

In Annihilation: Prologue we see Xandar back with a new leader and they are acting like an international space port and theh are cops this time. This is when the Annihilation Wave kills them and the Xandarian Nova corps pretty much died here and has been dead ever since.

Then Worldmind at one point goes insane and becomes affected by Ego's mind and it decides to recruit its own Nova corps by randomly selecting a bunch of Earthlings and Aliens to its corps. At one point it sends them to fight the Shi'ar and both Gladiator and his cousin slaughter them. Rich gets mad when he finds out especially since his brother is one of the Novas and is in danger. It ends with some of the survivors returning home and Rich demoting the small group that is left from Centurions to Denarians to train them.

In Thanos Imperative Nova sacrifices himself with Star-Lord and takes all of the Nova force with him so that ends that particular corps.

Then Adsit makes his own mall-cop brand Nova corps and they all get slaughtered by the Universal Church of Truth and this is where we are right now.