Annoying Video-Game Helper: No matter what you are up to, the Claptraps will keep bugging you about new missions that are available. It even gets to the point where they will repeat it AGAIN after you move to another region! The only way to shut them up is to go to whoever is offering the mission and accept it.
Slither, the boss of the "Altar Ego" quest chain. He's basically a repainted, somewhat faster than usual Scythid Crawler. In other words, an extremely tiny and weak mutant cockroach.
The Destroyer, the final boss of the entire game. He's slow, has a number of blind spots, and with the proper SMG or Machine Gun can be bled to death in short order.
One-Eyed Jack if you're driving a car, as you can just run him over. You may do so accidentally, as it's possible you came screaming in in a Runner and splattered him all over the hood without even realizing.
In the Zombie Island DLC there's also a subversion in Dr. Ned, who goes down quite easily. The credits then start flying by, only for Undead Ned to rip through the credits and scream "It's not over yet!", followed by the character introduction screen "Undead Ned: HOLY F*#KING SHIT!!!"
And then played straight again when Undead Ned isn't a very dangerous boss either, despite his intimidating appearance.
Were Skag and Skagzilla can be killed in ten seconds or less. Skagzilla only needs a powerful weapon with a high firing rate, while with the Were Skag, you can use a weapon with corrode and spray it with a powerful shotgun.
In the Claptrap DLC, the optional quest boss, Cluck-Trap. It's a gag boss that's as weak as all other Claptrap Mooks.
There are bosses that can be exploited due to map design or spawn point. Master McCloud won't even move from his entry spot if you die and respawn fast enough, thus causing him to stay in the same position until you leave the "corridor" to enter the "arena" and not even try to attack, but his sidekicks WILL attack you.
And the "Oh-so-hard Undead Ned"? If you enter the arena carefully you'll see him STUCK behind a rock and UNABLE TO ATTACK YOU. Once you see this, aim in his direction, keep jumping without moving, and empty your guns on him.
Helob and Widowmaker are two named spiderants who you need to kill for a certain mission. You can just run them over with a runner (though the runner needs to be at full health to survive each one.)
Broken Base: About the occasionally rampant modded weapons.
And the game's move from realistic looking graphics to the comic book style.
When it was announced that Borderlands 2 and The Pre-Sequel!, but not this game, were announced to be getting an Updated Re-release, fans of this game were questioning the lack of it. Randy Pitchford's response was, essentially, that it would only happen if the collection sold well on PS4/Xbox One. Fans of this game were enraged that they're essentially being blackmailed for the possibility of this game getting a re-release. Eventually, a new updated release of the first game's Game of the Year Edition was finally announced to be coming for PS4, Xbox One, and Windows in 2019, tempering flares a bit.
Gatling turrets and Mulcibers boast extremely long range that turns infinite once it gets a lock, and can only lose its lock if you leave its line of sight for an insane amount of time. This is exacerbated by the fact that most of them — especially the earlier ones— are out in wide-open areas with little cover. Hope you like sniping.
Psychos, when they swap the axe for a grenade. Though it also counts as a Funny Moment if said Psycho decides to whip out the grenade... at a point where it'll take more than the 3 seconds of the fuse to reach you.
The Crimson Lance probably qualify in some regards; they are by far the most dangerous class of opponents in the game due to their higher-quality firearms, higher chances of coming equipped with enhanced shields/grenades, and body armour that absorbs a lot of damage and is best worked around via Boom, Headshot!, Groin Attack, or Kill It with Fire (or acid)... or all of the above. Their Badass incarnations have heavy armour all over them, and can literally only be hurt by Boom, Headshot! and Kill It with Fire (again, or acid). Woe betide thee if you get ambushed by one that has a Combustion Hellfire...
Drifters in Secret Armory. 50 foot tall spider-things that eat cars for breakfast. There are few things in this game that are as terrifying and skin crawling as getting your vehicle destroyed by a group of them who then proceed to whale on your sorry hide. What's worse is they don't make a sound when they spawn, see you, and/or approach like everything else in the game. They do make a quiet cough-like growl as they attack, but by then it's too late.
Oh God, Drifters are frightening. They'll kill you in one or two hits when you're on foot, so naturally, your instinct is to run for a vehicle... which they can easily destroy with their acidic saliva. Oh, and using the vehicle turret's lock-on function makes the Racer and Lancer blast ineffectually at their feet. Your only hope is to be in a Monster, locked on to the Drifter, constantly firing homing missile barrages behind you as you get the hell out of there. That works fine when there's one of them... Strategic retreat.
Skags. They're annoying in the first playthrough, but manageable. In the SECOND playthrough, they become death itself, especially when Hardened Alpha Skags become common. Imagine trying to take down something roughly the size of a tank with huge amounts of damage reduction while being surrounded by lots of smaller ones who are constantly spitting Interface Screw acid at you AND others are pouncing you from all sides. Not fun.
Defilers from the Zombie Island DLC. Not only are their attacks hard to avoid, but their spread spew attack greatly slows your character and almost completely obscures your screen, making you a sitting duck for the horde of zombies that always accompany it.
By the same token, a lot of Marcus' and (to a lesser extent) Zed's quips when you use the vending machines.
Can't shoot enough bullets from your favorite gun? S&S has the solution: More Boolets! Four!Hundred!Percent!More!AWESOME! Also, Torgue doesn't make their guns out of freakin' wood.
Ensemble Dark Horse: Steve, a bandit from the trailers whose only real characteristic is yelling out "Heyyoooo!", whose popularity caused him to appear in the Zombie Island DLC and in the trailer for the Underground Riot DLC. He's even in the Secret Armory DLC as "Mini-Steve". He even appears in the sequel during a quest as an ally of the Zaford clan saying his iconic line.
Goddamned Bats: Rakk and scythids. These guys are cannon fodder in every sense of the word, being so flimsy they don't even have critical hit spots and pathetic attackers. You'll see how annoying they are when you're dealing with them and real threats (like bandits or spiderants) at the same time and they keep distracting your hearing with their cries and knocking off your aim.
In the third DLC, there is a way to access the armory without the time limit usually imposed on you. You can get unhindered access to 100+ chests because of a glitched section on the floor.
With the way multiplayer saving works you can dupe your weapons rather easily and sometimes by complete accident.
And of course, the patch of floor that makes you invisible to Crawmerax. Basically the only way to defeat it in solo without using Lilith.
Speedy Brick, achievable by starting Berserk and then immediately cancelling it (either by going to the Inventory tab, getting inside a vehicle, or going to FFYL), giving Brick Berserk's speed bonus indefinitely until you re-activate Berserk.
Good Bad Translation: In the French and Spanish versions, Steele is still casually talking about putting you to jail while the Destroyer impales her because the voice actors take too long. The same happens with the psycho who gets stabbed by M.Shank in the third DLC.
Scooter's "CATCH-A-RIIIIIIIIDE!!", which repeats every single time you get close to one of his Catch-a-Ride stations.
The canned ads that play whenever you access any vending machine, but especially Marcus'. There's only a small handful of lines they spout, so those repeat over and over and over again, and you've no choice but to use the machines as there's no other way of selling off your Vendor Trash. It gets really old really fast; like, within the first hour of gameplay.
Just about anything Claptrap says. Worthy of note is how they talk about new available missions every time you enter a new zone.
Midgets, who squeak and babble in extremely high-pitched voices.
Scythids make a sound like a scalded cat as they leap at your face. Rakk aren't far behind with their high-pitched squeals.
Nausea Fuel: Every single thing about Zombie T.K Baha, from his obsession about brains to the way he rewards you after you complete his Fetch Quests.
Paranoia Fuel: Is a midget with a knife going to jump out of this chest when I open it? Is a midget with a knife going to jump out of this toilet when I open it? Yeah, it's that kind of game.
An extremely odd variety of Player Punch, as it's a punch from the gameworld rather than a character death. Pandora being what it is, most of the other characters don't react with sorrow. You know, since the average lifespan once you hit Pandora ends up being a very small number of weeks. The game also doesn't do anything with it in terms of storyline afterwards; there's no investigation or revenge beyond immediately slaughtering another band of psychos.
The effect is diminished slightly when he's still sitting outside the building giving out quests due to a glitch some players encounter. It's even more diminished when you meet Zombie T.K. Baha at Jakobs Cove during the Zombie Island of Dr. Ned DLC.
Also, Marcus in Robot Revolution. He gets better though.
Launchers. Their damage is pathetic, like you're shooting off fireworks instead of high explosives. It doesn't help that they're extremely slow to both fire and reload, and their mag capacity is laughable. Only one kind is Not Completely Useless: Helix launchers, that fire three rockets in a spiral pattern for the cost of one, are a death sentence against vehicles. Otherwise, you're far better off using so much as a white-titledrevolver, even if you don't go crit-hunting.
Sleeper Hit: As Pitchford noted in one interview, the game actually sold better as time went on, compared to the usual pattern of a burst of sales at release, and it was all thanks to word of mouth. This is one reason why the sequel got a much bigger budget and proper advertising.
Spiritual Licensee: With the game's main focus being on collecting and playing with a seemingly endless array of brightly colored, ludicrously overbuilt guns, it's probably fair to call it the best Nerf game ever made. Especially considering the cheerfully violent and absurd story and creatures feel like the kind of things preteen boys would come up with while playing with toy sci-fi guns in their back yard.
Crawmerax the Invincible, which players only attempt to kill because he drops pearlescent weapons. The developers even lampshade how hard it is by calling the mission to kill him "You. Will. Die."
Also from the Secret Armory DLC, Knoxx himself turns into this after your first playthrough (at which point his level adjusts to 2 above yours): He's incredibly strong, but the problem is that he spawns Medics to heal himself. If you die horrifically (as you easily might while trying to kill the medics before they heal Knoxx) the medics will heal him to FULL HEALTH AGAIN. After taking out the medics and going back to killing him, there's a good chance he'll spawn more Medics if you don't kill him fast enough.
Mothrakk and Rakkinishou take a ton of punishment to down, can deal a lot of damage quickly, and their aerial mobility means running on foot is hopeless. Even Runners have a hard time hitting them, even locking onto them. And you're given absolutely no warning about where the latter appears despite having to enter his turf for a side mission.
That One Sidequest: Most critter-based elemental bosses tend to be rough in the early segments of the game, but aren't required to progress. Moe and Marley and Mothrakk are the standouts.
The second Circle of Slaughter series is aneurysm-inducing unless your character either has an impenetrable shield or insane weaponry. To be fair, the first playthrough's version isn't that bad with some luck and persistence, but the second time? -shudder-
The Underdome is a HUGE pain in the ass if you play solo.
Farming Claptraps for the collection achievements in Robot Revolution. Especially on Playthrough 2.5 where you can die in the blink of an eye from being blasted from all directions by Vladof shotguns with Cheating Bastard levels of accuracy. Also, every time you die, the Hyperion soldiers come back.
They Wasted a Perfectly Good Plot: In its original, less cartoony version, it was to have a plot told via cutscenes. This concept was left by the wayside after they decided that the new art shift would fit their original concepts better. One Gearbox member reportedly left developing games entirely because of this. Whether or not this move worked in the grand scheme of the game, however, is a minor point of contention.
The Woobie: Dr. Patricia Tannis. Her first ECHO journal recordings paint a picture of a sociopath who cares little for her colleagues, but as the game progresses they shift to show a fairly poignant, if humorous, picture of a brilliant scientist who has thrown away her sanity in search of a mystic treasure vault that doesn't even turn out to have treasure in it. She is lonely enough to have conversations with corpses, or to hope that the violent convicts who infest Pandora will be her friend, or eventually to build an android duplicate of herself to have someone to talk to. That poor woman.
General Knoxx. Tannis is nuts, but this guy just wants to die and the rebel Claptraps just won't let him.