Your longest boss fight

[Cheesebob]

A friend of mine was killing the final boss of persona 3/4 (I can't remember) it took him 5 hours to get him to 1 health bar. It used charm on his healer dude, which healed the boss and gave him back his 30 health bars.

My friend turned off the game and watched the ending on youtube, just as that happened

 

[SamuelT]

Any large bastard on Monster Hunter: Freedom; Unite. They take massive, and I mean massive, amounts of HP and Attack power when you meet them on the appropriate level and they will kick your arse if you don't pay attention the entire time. The horrid thing is that if you lose them during the battle for as little as five minutes they regain the entirety of their health - and if you fall during battle three times you fail the fourty-minutes-battle, losing anything you used and losing the amount of money you had to pay to start the mission.

The only good thing is that if you kill them you can carve their bodies up with a massive knife.

 

[subjectseven]

Yiazmat in Final Fantasy XII. 7 hours. It took everything I had because I was at quite a low level. Definitely one of my personal best gaming achievements.