Maybe not a pushover, but I died an embarrassingly large number of times.

In Elden Ring, some of the evergaols and bosses wandering the worldmap were harder than actual bosses. Ringleader's Evergaol took me like 10 tries.

The dancer in DS3 made my wife and kids check up on me.

Lady butterfly. Died 47 times against her. I'd always dodged instead of parry in soulslikes, and she kicked my ass over it.

The second phase of the final boss in Elden Ring.

Not because of the actual fight.

But I struggled the whole game with the extremely narrow FOV and motion sickness from that, and during the final boss, the FOV was actually too small to fit the entire boss during its animations or look at it when it rises (I think they later extended the camera max motion upwards in a patch?), and that excaberated the issue massively. And beating that boss while feeling semi-sick constantly was just not a nice experience. :(

In the whole EldenKingsSekiroSoulsBorne catalog? Or are we including similar games and expanding to EldenKingsSekiNiohLiesOfSoulsBorne catalog of games?

Seriously, I don't understand why we don't just refer to this genre similarly to games spawned by Rogue

In dark souls 2 the pursuer killed me so many times I almost quit. I don't know what it was about that fight but I could not beat the fella.

Also in dark souls 1 I got killed by Havel the rock so many times and once I killed him and found his armour it held a special place in my heart. I'd try to wear as much of it as I could without fat rolling. Which usually left me wearing no ar in some slots.

Deacons of the Deep in dark souls 3. I was running a light dex build at the time (I think using a rapier?) and it was a bit of a nightmare.

The boss is supposed to be piss easy but if you don't have any sweeping attacks it quickly becomes unmanageable becauss you can't kill them fast enough and they keep spamming annoying spells.

Dark Souls 1 and it was Chaos Witch Quelaag. I don't know how many times she killed me, but it has to have been over 20. I got destroyed over and over again.

I was literally going to say crystal sage before I read your full post. I've never once gotten through a DS3 run without dying several times to him, and I've probably played a dozen or more times. Even with the throwing knives cheese.

Haven't yet beaten Malenia. Not even close. Just a lot of bullshit mechanics i can't deal with.

Also on Crystal Sage: I found it funny how he was an absolute pushover for my first character (melee build) and a pretty hard challenge for my second (magic)

The first Headless I encountered in Sekiro. I was seeing enough progress and understanding what was being asked of me just enough to be stubborn as hell and kept trying to fight it head on, without having any knowledge yet of any helpful items that make the fight less rage-enducing.

Outside of Fromsoft, my NG+ encounter with the green swamp monster thing in Lies of P seemed SO much harder than the first time. So I'm not sure if this boss is considered easy or hard, but I didn't consider it to be very hard going in for a second time and got quite stuck for a while...