Mega Man 1/YMMV


 * Anticlimax Boss: Both phases of the Wily Machine battle are almost insultingly easy after the hellish boss rush that comes before, not to mention how hard the game is in general. He only has one method of attacking in both phases, and both are easily dodged (phase 2 less so, but still quite easy).
 * Breather Boss: Bomb Man and Cut Man are both this. Their stages are probably the easiest in the game, and both aren't hard to read unlike the more unpredictable bosses (Looking at you, Elec Man!). Both of them have easy to dodge weapons as well, and rather simple attacking patterns.
 * Demonic Spiders: The infamous Big Eye is easily the hardest enemy to deal with in this game. They are ridiculously sturdy (It takes around twenty shots of the Mega Buster to kill one, and take away one third of your health from the collision damage that they deal. What makes them this though is that they're incredibly unpredictable: they jump either high or low, and you can only run under one during a high jump and there's no way to tell which one they'll do until it's too late. Unfortunately, they appear at the end of almost every Robot Master stage, and in the first Wily level, there are THREE that you need to get past.
 * Ensemble Darkhorse: Guts Man is often considered the most iconic Robot Master from this game, if not the entire series. Not surprisingly, many people were pissed that he didn't make it into Dr. Wily's Revenge for the Game Boy (and, by extension, any of the Game Boy games). Heck, his popularity may have contributed to him being a Wily Castle boss in Mega Man 2 (As a tank) and in Mega Man 7 (Heavily modified and still tank-like), as well as a main character in the MegaMan Battle Network series.
 * Cut Man as well, along with Guts Man he's also considered among the most iconic Robot Masters of all time, and is probably remembered fondly for being the Robot Master people usually battle first. It's worth noting that he's appeared as a boss battle in one of the versions of Mega Man 8 as well as a secret boss in Mega Man X8.
 * Game Breaker: Not to the extent of the Metal Blade of course, but the Thunder Beam is ridiculously powerful: you'll tear through pretty much everything with it while a small amount of ammunition is used. And with the pause trick combined with the Thunder Beam, tricky bosses like the Yellow Devil become moot points.
 * Goddamned Bats: Bladers, spastic helicopter enemies that move slowly until they come close, then they suddenly rush you with barely enough time for you to react. In Wily Stage 2, they'll do all that they can to drop you into the bottomless pits below.
 * Ditto for Fleas, which are awkward to hit thanks to their small size and the speed of their jumps.
 * Flying Shells, especially in Bomb Man's stage. They can only be hit whenever they attack, and they shoot an eight bullet spreadshot that can be tricky to dodge. Even worse, they respawn almost instantly when defeated, and in Bomb Man's stage, they appear en masse while you maneuver over death spikes, and you WILL die if you touch them since mercy invincibility won't save you!
 * Goddamned Boss: Those who don't think that Yellow Devil qualifies as That One Boss will view him as this. His separate/reform pattern actually follows a very simple pattern, but the fight goes on forever without using the pause trick thanks to the fact that he's invincible for most of the fight, is only vulnerable for enough time to get one shot in, and can make it to where his weak point can't be reached by any of your weapons. Ultimately, he's not hard so much as he is incredibly tedious.
 * Good Bad Bugs: The famous "Pause Trick" glitch, which allows you to rapidly pause the game while an attack like the Elec Beam is passing through an enemy, allowing them to take multiple bits of damage from the same shot. This is often used by gamers to beat...
 * Harsher in Hindsight: The encouraging words at the end of the game "Fight, Mega Man! For everlasting peace!" are incredibly depressing whenever you take the Mega Man X and ESPECIALLY Mega Man Zero series into account, as everlasting peace was never accomplished.
 * Polished Port: The Wily Wars rerelease.
 * Scrappy Weapon: Both the Hyper Bomb and Super Arm fall into this. The Super Arm isn't bad per se as it deals a ton of damage and has a scattershot effect... but you can only use this weapon by throwing designated blocks that are laying around in several stages. Keep in mind, not every stage has these blocks which means that this weapon is hurt by how situational it is. As for the Hyper Bomb, it deals a ton of damage, but good luck hitting anything with it since the bombs take a while to explode, and your target will very likely move out of the way before it does so. It's especially infuriating since Bomb Man could make his bombs explode on contact while yours can't.
 * That One Boss: Yellow Devil, Yellow Devil, YELLOW DEVIL. Many gamers throughout the years have never been able to conquer this infamously tough boss without exploting the "Pause Trick" glitch.
 * Elec Man and Fire Man become this if you fight them without their weaknesses. Elec Man is incredibly spastic and unpredictable, and his weapon the Thunder Beam has huge hitboxes and can kill you with three hits. Fire Man on the other hand simply blasts at you with his weapon constantly. It's incredibly fast and hard to dodge, and comes at you in random intervals.
 * Ice Man isn't easy as well. While he does attack in a pattern, you need precise timing to dodge his Ice Slashers, or else you may as well kiss a third of your health goodbye.
 * That One Level: Iceman's stage, if you're doing it without the Magnet Beam. There's a large chasm you must cross on Foot Holders, moving platforms that drift back and forth at random intervals. In addition, they fire at you while this is going on and it's perfectly possible to fall right through one. And then about halfway across, Pengs will start to Zerg Rush you. Without the Magnet Beam, it really starts to feel like a Luck-Based Mission.
 * Wily Stage 4 is another one, mainly for having an incredibly tough boss rush with Bomb Man, Fire Man, Ice Man, and Guts Man right before Dr. Wily with no way to heal yourself in-between battles and no checkpoints in between the Robot Masters. Thankfully, the small area in between Guts Man's and Dr. Wily's rooms counts as a checkpoint, and Wily is so easy that he more than makes up for the previous bosses.