Boss fights are fun, and everyone loves Megalovania, but did any of you fail to stay determined when faced with Sans?
Personally, I haven't attempted a Genocide run, but I'd like to imagine that he's managed to stop at least a few rampaging player characters from erasing the universe.
I included all the possibilities I could think of. (#4 and #5 are basically Papyrus and Undyne.) Leave a comment if your experience was different.