Most of the bosses seemed fairly easy where I could beat each in two or three tries or even in one.

The hard bosses? I thought Four Kings was fucking ridiculous. You have to be able to deal massive amounts of damage in a short time while also reeling from their massive hits. The only way I managed to do it was by completely disregarding a shield, putting on the heaviest armor in the game, and swinging away while chugging the 20 flasks I had. If you can't kill at least one of the kings before the third one pops up, you're basically done for. I did manage to beat them in three tries but my adrenaline was pumping the entire time. Maybe it was also because the bonfire was so fucking far away.

All-time hardest would have to be Gwynn, Lord of Cinders. He took me a grand total of ten tries. It's a fight where you CANNOT fuck up. You can only hit him once (AND ONLY ONCE) safely when he tries to grab or when you're close enough after he does a kick. He's fast as fuck and even with 190 stamina, his chain attacks would break through my shield and deal 1/3rd of my life bar. If you need to heal, you have to wait for a very slim opening and if you don't hit that opening correctly, he'll smack you really hard. The rocks around the room were a god-send because you could strafe around and he would hit them instead of you but it wasn't guaranteed. Also, I do not see how you could do that fight without the back-flip ring. The regular rolling animation takes way too long and isn't fast enough to effectively dodge his attacks. I ended up dying numerous times on his last sliver of health because i would accidentally roll into a wall and if you can't keep moving away from him, you're fucked.

So, who did you find hardest?

4 Kings so far for me.

@CaLe said:

Smough and Ornstein. Not the first part but the second because I didn't hit for much damage it had a lot of health so I had to move a lot and it took a long time. Had no trouble with the 4 kings or Gwyn.

Didn't have much of a problem with S&O. Got completely destroyed on my first attempt but realized lighting damage does a ton to Smough and I happened to have the lightning spear. It helped to use a spear since you could attack Smough without dropping your cover which would prevent Ornstein getting a free hit. Once Smough was down I just switched to Quelaag's Furysword and went all out on Ornstein. Went behind a pillar if i needed a heal since he just tosses lightning bolts if there's enough distance between you and him.

wow i found gwyn to be easy , but im mainly comparing him to false king allant in demon's souls , who was alot cheaper than gwyn , but it was a similar fight.

also in ng+ i just summoned solaire on gwyn and he distracted him perfectly so i was able to just spam attacks in his back when he turned around ..

bed of chaos just annoys the fuck outta me with the reach on his hands but its not hard to kill , and being able to complete it over multiple lives is kind of a cop out eheh.

priscilla would have been harder if quelags furysword didnt expose her in like 3 hits .. or any fire for that matter ..

four kings i guess is just a gear check .. if you cant withstand thedamage or output enough .. its nigh unwinnable .. but it IS easy once you can overcome these things ..regrettable easy when you overprepare for it like i did

ornstein and smough and the bell gargoyles both get increased difficulty from the additonal targets , four kings i thought would be way harder but its a much simpler shared lifebar mechanic

quelaag on new game+ gave me some problems but i adjusted for fire defense and made it through fine , same with any fire boss really i just dont like fire eheh .

honestly i dont know which boss is truly the hardest .. id say the last few bosses are only difficult because of the areas you need to traverse to get to them .. where as the intital bosses are harder because youre less prepared for them.

i dunno .. has anyone actually fought Ceasless discharge without glitching him ? he might be hard ehhe i didnt even try :/

@envane:

the only way to fight him without making him fall into the pit is to aggro him, haul ass into the valley-type-thing nearby, stay in his sight till you notice him begin his attack animation, run behind the rock and when his tentacle comes down, run to it and hit it until it goes back up. Rinse and repeat. I've done it both in my first playthrough and in NG+ and he didn't hit me once.

Also, I don't know why Gwynn was insanely hard to me but not so much to you. If he hits you with any of his attacks, they easily take off 1/3rd to half my hp and I have to be VERY careful until there's an opening to heal. The only time I found I could heal safely is when you put a rock between you and him and wait for him to jump back in preparation for his massive leap attack. The rock stops him from hitting you and you can heal but it doesn't happen incredibly often and I was in incredible danger waiting for said chance.

And fuck, he's on your ass 24/7. He does not let up and if you don't dodge at the correct time, his sword can nick you, throwing you off balance and potentially allowing him to fuck you up if you can't dodge or block in time for his next attack. I just thought he required an insane amount of concentration that wasn't required of the other bosses.

4 Kings. It's totally unfair that you have to fight 4... Kings at the same time if you're too slow. And even if you do kill one, they'll respawn!

@Fribain: Yeah I beat him but by cheesing his AI routines in the L-shape alleyway. I posted my "triumph" in the Boss Strategy thread.

Gwyn was beating the shit out of me for awhile. I was terrible at my attempts to parry him to death. Then my roommate walks in and asks if I tried my pyromancy. I am all "No way. Like Gwyn is gonna get killed by fire." Derp, he's dead after like 20 seconds of Greater Combustion spam.

Smough and Ornstein probably killed me more though.

@Fribain: Gwyn was easy once i figured it out. 5 hits, he went down in 5 hits. Block first attack, parry second, ripost 1/4 GONE! If he goes in for a grab, dodge. Then walk back into close range to bait his attack and repeat until he dies. Using a Black Knight Shield would also be a good idea.

And yeah, Smough & Ornstein or Four Kings are probably the hardest bosses, especially on NG+. S&O can be even harder if you do it in the wrong order. NG+ Four kings ist just kinda bullshit.

@Shirogane:

hm, i never knew about that strategy. I was using a tower shield, though, so i wouldn't have found out about it anyway. Fought him the old fashioned way of dodging him for a good 15 minutes and going in for one hit at a time. it was excruciating

Already have a fairly long thread for this:
http://www.giantbomb.com/dark-souls/61-32697/hardest-boss-youve-faced-so-far/35-519686/#69
 
A far as Four King's go, I didn't find them hard at all and blew through it on the first try. Pretty much killed every king before the second one spawned. Except for the last King, he came in as I was halfway done with the 3rd.
Gwynn's dammage can either be tanked through, or you can kill him easy with riposte.