A large Scale Event that Effect Whole Galexy

While yes, some aspects like an endgame cataclysm would be fun, this isn't supposed to be Stellaris 2.0.

I don't mean like necessarily end game events like random events that could happen like as i mention say like a plague or virus. If something like that took place in game *hypothetically* it could disrupt trade routes or hinder the military or planetary defenses of a per say planet or fleets. Getting the cure you could take advantage of the other factions and charge them more or less for the antidote if they wont pay they would either succumb  to the virus, betaken over in their weakened state or, develop their own cure. Idk if something alone those lines would work but that is one of the examples out of many that could be proposed for a large scale event. Or something like that.