Too many to list specifically...
Off the top of my head, most common endgame killer for me is probably cat lord or Nurgy, probably with around 10 deaths each. After that... I've had bad luck with berserking ancient dragons and wyrms and probably have another 10 deaths between the various species. After that is probably balors/fisty, with maybe five, and Andor, with about the same. Ghost lords/kings as well. Probably close to 10 there. Doppleganger kings... maybe five. After that... A few from golems, diamond and eternium. A few from Earth Temple monsters, though not ASB. A few from quickling queens. At least one by a werewolf king. A couple from shopkeepers. One or two from mimics, I think. I'm sure I've been killed by a greater moloch before, and a (greater) titans. Maybe one or two from ancient blue wyrm and a couple from mommy water dragon. Emperor lich is likely. I've been through the endgame enough that I've seen a few deaths from almost any seriously dangerous endgame monster, I guess.
Hoping to win with every class, doomed. Archer, Barbarian, Bard, Beastfighter, Druid, Elementalist, Farmer, Fighter, Monk, and ULE Priest down.