robio said:

Not quite the worst final boss, but the Dark Dragon in Tokyo Mirage Sessions needs to be mentioned I think. TMS has a really fun combat system for a turn-based RPG, but at the end of the day it is a turn-based RPG and the Dark Dragon boss is over 20 minutes long. Probably closer to 30. It's a tough battle, but the sheer length of it makes it very annoying.

This reminds me that I really need to get back to this game. I was really enjoying it but got sidetracked with other games. I think I might have gotten about halfway in it but not sure.