- Metroid Prime : The Omega Pirate is one of the first insane boss that sprung to my mind

- On the contrary, Salazar in RE4 is the easiest to kill. 1 Rocket and 2 or three shot from the magnum. Less than 2 mn.

Red -- Pokemon Gold

Mainly MH3 Bosses, never played a game as challenging before

Probably the 6th boss of R-type delta in hard mode.

the giant robot thing in TimeSplitters 2

well if were talking recently, barthandulous on ff13 was a fucking pain. i thought i was going to loose my mind, after 3 days of guides and youtube vids i finally managed it.

Sephiroth wasn't hard. 

Kurt Zisa was harder than Sephiroth I think. He sealed your fucking magic and became immune to physical attacks after it was unsealed.

Anyway, Sephiroth just has a long sword, nothing else. Determine the range so that he can't hit you.

He's not dangerous at all in his first phase.

His second phase is. But if you have Strike Raid and have him locked on, Descend Heartless Angel isn't a problem. Omnislash is the fucking problem.

Then his third phase isn't a problem.

If you know his attacks and know how to dodge them, he's not a problem. I beat him about 25 times in a row because he was the fastest way to get to Level 100.

Oh, I forgot to list mine.

Final Fantasy IV - Zeromus. Took me at least 17 tries. I got really pissed since you have to go through half the dungeon to get to him.

Final Fantasy IX - Necron. Grand Cross. 'Nuff said.

Erm.... I forget what else.

When I was young I couldn't beat N. Gin in Crash Bandicoot Warped. I got scared of the big-ass health bar and asked my dad to beat it.

Henry in No More Heroes on Bitter Mode was a bitch.