Difficulty in video games is about as subjective a topic as - well just about everything else in video games. What's crushingly difficult to one person may be a total breeze to someone else, and vice versa.
But as with every rule, there are exceptions. Some bosses really are just utterly broken.
There are some boss fights out there that no gamer can comfortably complete alone without some amount of outside assistance. Whether it be because the boss has a gimmick that the player has no means of adapting to before they die, or because the solution to beating them is so vague you'd need someone with three physics degrees to help you decipher what the game actually wants you to do.
These boss fights should be considered outright flaws in the games they inhabit. Because if you genuinely do need a guide to get through a boss fight, then the game hasn't properly communicated to you what you need to do to succeed in a way you can understand in time to avoid the boss' insta-death laser.
It's not us, it's them: honest.
10. Wolverine - Spiderman: Web Of Shadows
This entry is at the bottom of the list because the fight itself isn't what's impossible - it's the questionnaire that's the issue. Let me explain.
Spider-Man: Web Of Shadows' main gimmick is the ability to switch between your red and black spidey suits on the fly. This also introduces a moral choice system, where Spider-Man has to choose whether to give in to his demons for the greater good, or rise above the symbiote's promises and compromise nothing. But when Wolverine believes Peter to not be the one in the driver's seat, he attacks. And when that doesn't quite work, he breaks up the fighting with questions about Peter's past.
So what's the problem here? These are some DEEP lore cuts, that most casual Spider-Man fans will never know. And it's not even like you could Google them at the time that easily, since not only are they obscure, they're also VERY specific. One of the questions is, I kid you not, "who fed us roast and pie?"
Okay, so you fail a few questions, you're probably still not seeing the issue. The issue is that failing a question earns you evil points. It's not even framed as Peter lying, but more like he just can't recall the VERY specific instance of dining with roast and pie that Wolverine is referring to, and Logan deciding that makes him a bad guy.
The fight isn't the hardest in the game, but if you're trying to go for the good ending, you'd better know your Marvel history, or that 100% good side run ends here, bucko.