Lyxen
Great Old One
Big cosmic opposed forces are rarely evident in D&D. You do not normally see examples of the forces of Cosmic Good against Evil the way Demons and Angels might be opposed in In Nomine or similar Heaven and Hell war cosmologies/stories. Similarly you do not expect to see stuff like the Moorcockian Courts of Chaos marching out to face the Lords of Law.
But we do. I think it all depends at what level you are playing. But not only are the players usually, towards the end of the campaigns, exactly on these battlefields, in some campaigns the heroes end up being the gods themselves on that battlefield, after ascending. This is for example what I'm pretty sure will happen in our Odyssey of the Dragonlords campaign, we are "only" lvl 8, but the prophecy says the gods will die and our only hope is probably to ascend to replace them and face the titans (at least some of them).
In core D&D we have the Blood War for some Chaos versus Law and a bit about the Lawful Vaati Wind Dukes versus the Chaostic Obyriths as Rod of Seven Parts lore. In Dragonlance there are the Good, Neutral, and Evil collections of gods in balance that clash as a central storyline while they are in the picture. Eberron has the Rakshasa Lords of Dust versus Coatls history war and to a lesser extent the three dragons alignment split and the Sovereign Host and Dark Six who are a bit opposed but not at cosmic war that I can tell, though I have not seen a lot of lore on their history and current machinations.
Eberron is far less manichean and meant to be played at lower level anyway.
For Planescape we have the Blood War again. For the Great Wheel settings of Greyhawk and FR (for a lot of FR history) there is no big alignment cosmic clash among the gods.
That's because the FR are diluted to the extreme and statu quo is maintained to avoid breaking everything the way Greyhawk went during the Greyhawk wars.
4e had big cosmic clashes but they were mostly not along alignment poles. The Dawn War Elemental Primordials versus Astral Gods is pretty cosmic but not Good versus Evil. 4e has a big cosmic Evil with Tharizdun and the Shard of Evil and Demons and Asmodeus but it is not Good versus Evil cosmically, it is the gods of every alignment chaining Tharizdun and sending Asmodeus and the devils to fight the threat of the corrupted evil of the demons. So Blood War again but much less directly a clash of Chaos and Law.
Just because published settings are a bit timid about such world-shaking events (and they are sometimes done in ways that the fans don't like, see the Greyhawk Wars or the Faction Wars) does not mean that it cannot be played that way, which is something that we have always done, either on published settings that we trashed (sometimes as designed, see Odyssey of the Dragonlords) or in homebrew.