That One Boss

"I can't defeat Air Man. No matter how I try to dodge his tornadoes, he just kills me again. And even though I can get behind him It's no use, I try to fight, but get blown away in the end. I shoot as fast as I can, But when I had to go against Air Man's tornado I was helpless again I'll try again, of course, but this is my plan: I'll keep my E-Tank in reserve just as long as I can!"

- I Can't Defeat Air Man (English version)

There are many different categories of bosses, some more memorable than others. There's the Giant Space Flea From Nowhere, there's the Climax Boss, the Final Boss...

And then, there's That One Boss, the boss that falls victim to poor playtesting. You're levelling up normally, plowing through every battle, until you reach this particular battle and suddenly meet a plethora of Game Over screens. Eventually, you Rage Quit, or you go on the Internet looking for assistance. In the event that you stop by the game's message board, lo and behold, everyone else is having the exact same problem, with entire topics asking "how do I beat That One Boss?". Walkthroughs usually list the worst offenders as "the hardest boss in the game", and eventually, such a beast receives a reputation for being just that freaking hard.

Certain types of boss are not usually included in this consideration right off the bat: The Final Boss, "Wake-Up Call" Boss, and Bonus Boss. People expect the Final Boss to be tough (usually), and the Bonus Boss is usually included solely to be difficult. However, it's still definitely possible for them to count if they're hard by their standards: sometimes a Final Boss presents a baffling difficulty spike in a game that has otherwise been smooth sailing since the beginning. A "Wake-Up Call" Boss might not even be a "wake-up call", but a cheap kick in the balls that is more unfair than what's to come. And as the SNK Boss shows, some Bonus Bosses can take the intended difficulty of a game's ultimate challenge and make it outright insane.

They usually show up in RPGs, though they're not exclusive to them. Game designers will sometimes go out of their way to put them in, serving as a bottleneck to make sure you spend a couple hours Level Grinding before you go on to the next area.

Occasionally, the identity of That One Boss varies depending on an individual's playing style - bosses are often designed to have issues with one particular strategy, so one that requires another strategy can seriously hinder a gamer if they're not prepared to switch up their tactics. So while Revive Kills Zombie can disqualify a boss from being That One Boss, players either unwilling or unable to use 'revive' can still have a hard time.

They are sometimes called the "brick wall boss", for obvious reasons.

Compare Demonic Spiders, which is more of a That One Random Encounter, as well as the Boss in Mook Clothing. We'll leave it up to you to decide which is worse. See also That One Sidequest and That One Level. Contrast Anticlimax Boss, where the boss is underpowered/easy for story reasons (or despite them), and Breather Boss, where the boss is just pathetically easy unintentionally. For bosses that are not technically difficult, but are downright frustrating, see Goddamned Boss. For bosses that are deliberately impossible to beat, see Hopeless Boss Fight. If you're looking to read up on unfair bosses that the game seems to deliberately give every known advantage to, requiring you to either get by on luck or cheap gameplay, head on over to SNK Boss.

Because there are so many examples of this trope, they have been categorized by genre for your viewing convenience.