For what it's worth, I hate that "save the universe" trope with a passion.
Universe-threatening but kinda' okay given the SF-context:
- TNG: All good things (though, again, Q messing, so it's not a "apes save the universe" story, it's a "god plays games with a tiny monkey" story)
As far as I can recall (and assuming it was real and not some Q illusion), that event was only quadrant-threatening. Of course, you can use the reasoning that the anomaly is bigger the further back in the past, and the universe smaller, it would at one point in the past have filled the entire universe. Still, the earth apparently was formed even under those conditions, so it's uncertain as to how much the anomaly would actually affect events (otherwise than apparently preventing life on earth).