That One Boss
I can't defeat Air Man.I'll keep my E-Tank in reserve just as long as I can!
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 Can't Defeat Air Man (English version)
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. Players will prepare for the Bonus Boss by overleveling, but for maximum frustration, That One Boss needs only to just show up out of nowhere, preferably having no place in the storyline beforehand.
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. However, any easy tactics like Revive Kills Zombie disqualify a boss from being That One Boss... unless the 'revive' itself is impossible to find.
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.
To sum it up. If the boss is difficult when you first get to him, but when you get enough skill (or understanding of the needed mechanics), it is easy on further playthroughs, it is merely a "Wake-Up Call" Boss. If it requires a very unusual tactic to win, but dies easily to it, that is Revive Kills Zombie. It has to be much harder than expected for that point in the game, and remain that way every time you replay the game to qualify as That One Boss. In other words, this is the boss whose battle will haunt your nightmares every time you see his image or hear his name.
It is useful to note that, as its name implies, most videogames only have one That One Boss. If a game appears to have several candidates for the title—especially if every boss battle feels this way—you are probably looking at Boss Dissonance (of the Kirby variety), or a game that is just plain Nintendo Hard.
NOTE: Final Boss and "Wake-Up Call" Boss cannot be That One Boss without being overly hard by their standards. Please do not nonchalantly add them as examples. An Early Bird Boss will almost always qualify as That One Boss as well, but for reasons of the player's weakness rather than the boss's strength, so those bosses are better placed in the Early Bird Boss article. Bonus Boss is completely banned from this page, as they are optional and they have to be overpowered. There is no measure for them.
Because there are so many examples of this trope, they have been categorized by genre for your viewing convenience.
- Atlus (No, this isn't a genre, but a company. Yes, a company makes games with so many sadistically hard bosses that it needs its own section.)
- Beat Em Up
- First Person Shooter
- Shoot Em Up
- Stealth Based Game
- The Chaos-Master from the 11th book in the Lone Wolf series of gamebooks. It's a hideously hard fight if you don't bring the Sommerswerd along. If you do? Chances are you will die horribly. There's a particularly infamous Let's Play of Book 11 that had the players redo the Chaos-Master fight twenty-seven times before they finally won. It's that hard.
- Not actually a game example, but in the manga The World God Only Knows, Keima Katsuragi can capture any girl... any girl... with the exception of Yui Goido. He himself notes she is a serious player, introducing a new meaning to Player vs Player. He eventually wins... by playing the Damsel in Distress.
- Ashley's boss microgame from Wario Ware Touched features borderline Bullet Hell patterns of projectiles to dodge and an end boss that has three separate pieces shooting things at you.
- Nethack hasn't got many bosses, but of those few that are there, the Wizard of Yendor is the most mind-numbingly annoying - and dangerous as well. His abilities include casting powerful spells (some of them capable of being instantly lethal) as well as stealing certain important MacGuffins and creating clones of himself. And as if that wasn't enough, he won't stay dead - even if the player kills him or escapes the level, he will periodically cast nasty spells on the player or even return to fight in person again until the player reaches the Astral plane.
- While the final bosses of the Ace Attorney series usually take longer to break than other culprits, the final showdown in Investigations gets special notice for being so long and difficult that there's a save point in the middle of the fight.