Royce Gracie vs Akebono. It wasn't in the UFC, so it doesn't get much attention. But this fight showcased what Brazilian Jiu Jitsu -or rather Gracie Jiu Jitsu is all about. (BJJ has become so sport oriented today, that pretty much the only people teaching BJJ as self defense is the Gracie Academy, right?)
I don't think many fighters would get in the ring with someone who outweighed them by 100 pounds. Imagine Akebono falling inside your guard. If you weren't flexible, he could totally damage your hips or groin. In this fight, Royce proved once again that Gracie Jiu Jitsu can enable a smaller person to defeat a larger opponent. It's my all time favorite fight.
Younger people (under 30, I guess) may not understand how impactful Royce Gracie was for those of us studying traditional martial arts. He was my Bruce Lee. Had Royce died in a plane crash around '96, I have no doubt his legend would surpass that of Bruce Lee today.