FFX final boss run, because I'm a sucker for fights with emotional significance. Yeah Yu-Yevon was kind of out of nowhere, but I think after Jecht it makes sense to follow up with a no-name. It's not about the thing they're fighting, it's about all the friends they have to sacrifice to fight it.

Safer Sephiroth, not technically the final boss, but what I like about it is the whole party participates. I like a final boss that brings in the whole party because why would you even be like, "ok you guys stay in the car."

Mass Effect 2, the (SPOILER)human reaper was really scary the first time I fought it. I didn't know how to fight it and it was so HUGE and would pop its head out RIGHT IN FRONT OF ME and shoot LASERS and it was very creepy looking.

Persona 3, because the arcana is the means by which all is revealed

FFVIII, SHE STOLE MY STATS DO YOU KNOW HOW MUCH YU GI OH I PLAYED FOR THOSE