Ultima and Omega Weapons (in FFVIII) are smurfing beasts of a superboss and they are brilliant. I love superbosses because it seems to me that "regular" bosses are not inherently challenging, they typically just take a long time to battle because of their hit points. The Weapons will straight up wreck your trout. I love fights in which I have absolutely zero hope whatsoever of winning and am holding on for dear life the entire time because it makes winning them so much more satisfying.

I seem to remember somehow thinking that Ultima Weapon in the Deep Sea Research Center was horrifically more difficult to beat than Omega Weapon in Ultimecia's castle despite the fact that their health points differ by literally a million points, but perhaps I have mixed the two of them up.