A little originality goes a long way
Tempest (Dragon Age: Inquisition)
Let's start with a recent (that is, still impending) standout: the Tempest subclass in Dragon Age: Inquisition. Of the three paths available to the Rogue, two are typical - Assassins are the classic shadow-stepping killers, while Artificers specialize in explosive traps. But the Tempest opts for a much wackier method of attack: chugging down homemade alchemical mixtures to imbue their bodies with elemental effects.
Your typical Tempest is like a guy who shows up to a knife fight, douses one arm in liquid nitrogen and the other in lit kerosene, and crazily charges into battle. That's amazing, and much more interesting than another variation of the dual-wielding dagger expert.
Ecaflip (Wakfu)
Coin flips, dice rolls, and Tarot cards: these are the tools of the Ecaflip's trade. Elements of chance and gambling spring up all the time in RPGs, like the slot machine Limit Breaks of Final Fantasy VII or the entirety of Unlimited Saga which should never be spoken of again. But these furry cat-people are by far the most interesting gambling warriors in RPG land.
Will your attack hurt your enemy, or heal them? Do you dare press your luck on a dice-rolling Winning Streak? The Ecaflip's iconic abilities all involve uncertainty, and the fact that they wield a deck of cards instead of a sword or crossbow is ace.
Onion Knight (Final Fantasy 3)
When I first discovered the purpose of the Onion Knight during a round of the Final Fantasy Warcraft 3 custom map (long story), I was floored. Here's a class that's seemingly worthless, with no special abilities to call its own. After abandoning it for cooler jobs like Red Mage or Ninja, you'll probably never think about the Onion Knight class again - and that's the beauty of it.
Yes, the Onion Knight is pretty useless - until you hit level 90, at which point it becomes godlike. You start gaining stats like crazy and become eligible to don the all-powerful Onion Equipment armor set, turning this job from the worst to the best just like that. Sometimes, it pays to get back to your roots.
Insect Glaive (Monster Hunter 4)
If you're not yet a disciple in the Cult of Hunting Action, then you should know that classes are defined by their choice of weapon. And while most of Monster Hunter's armaments are pretty typical fare, like the Dual Blades, Long Sword, or Hammer, the Insect Glaive is anything but. Imagine a giant polearm with a carapace-like cannon on one end that shoots out a huge bug to do your bidding.
Your little Kinsect buddy will lock onto your monstrous targets when you shoot them with a pheromone bullet, pestering them while you lunge around like a murderous Olympic polevaulter. That's positively insane (and insanely awesome).
TaeKwon Master (Ragnarok Online)
Ragnarok Online is full of incredibly niche classes, but this one is just nuts. You'd think that TaeKwon Masters would simply be martial arts experts in spiffy gis, but playing one demands intimate knowledge of the Sun, Moon, and Stars. Your abilities may or may not be usable depending on the current day, your location in the game world, and a monster's given alignment to a celestial body.
Let me reiterate: the real-world calendar date affects the way you play this class. Knowing the right balance between your Solar, Lunar, and Stellar abilities actually requires you to be in tune with the universe itself - or at least be cognizant of what day it is during your week-long grinding sprees.
Arithmetician (Final Fantasy Tactics)
If you want to utilize the Arithmeticians to their full potential, you better step up your mathematical game. Each spell cast requires some premeditated calculations on your part, because hitting the correct targets requires that you crunch numbers like a champ. If you want your almighty Holy magic to hit only enemies and not your allies (or yourself), you'll need to factor in things like character level, XP, or the current elevation of every character on the map and whether that number is a multiple of three, four, or five.
I can think of no other RPG class that rewards you for possessing intimate knowledge of prime numbers. Truly, you are killing people with the power of math.
Entertainer (Star Wars Galaxies)
Some folks want to become one with the Force; others want to smuggle precious goods across dangerous territory. But you just want to dance. Star Wars Galaxies - Yoda rest its dead servers - had one of the most mind-boggling class outliers ever in its Entertainer profession, asking that you put yourself out there in front of virtual crowds of players and dazzle them with your rhythmic talents. That's literally how you level up.
It's not enough to just AFK in one spot with a dance animation, either - you have to know how to impress onlookers for extended periods of time. As a class that rewards you for decrypting the social psychology of other people in an MMO world, it may very well be the most complex role-playing experience in any game, ever. I mean that.
Puppetmaster (Final Fantasy 11)
Necromancers raise the undead to fight on their behalf, and Hunters have trusty animal companions. But those pet types are so played out - why not attack enemies with a marionette-like Automaton instead? Pulling on unseen strings in the thick of battle, Puppetmasters get up close and personal with monsters using clawed weapons while their hollow-faced wooden companions support them from afar. It's like the creepiest, most dangerous puppet show on the planet, and that's saying something.
It's not easy walking the path of the so-called PUP, since it requires deep knowledge of FF11's systems and a hefty chunk of in-game change. But persevering means having the satisfaction that you and your loyal puppet pal terrorize monsters like battle-hardened versions of Gepetto and Pinocchio.
Maniac (Atlantica Online)
Like Monster Hunter, your choice of class in Atlantica Online depends on your weapon. Sword, Spear, Gun, Bow, etc. I get - but what the heck is a Maniac? That, dear reader, is what you call someone who wields a chainsaw sword in a medieval fantasy world. You can only access this class once you've leveled a character to 100, but the reward is the ability to slice through swathes of enemies with a power saw. I'd say that's a fair trade.
The mere sight of a Maniac in-game justifies its existence as a class. Here's a warrior who looks like he's clad in ornate armor made during an ancient Chinese dynasty, wielding a fantastical, viciously toothed chainsaw like some kind of insane, time-displaced horror movie slasher. I... I think I'm in love.
Herald of Xotli (Age of Conan)
Battle mages are inherently awesome - hybrid spellcasters that would rather get down and dirty in a close-up brawl than shoot fireballs from afar. And of this somewhat niche archetype, the Herald of Xotli might be the coolest of them all. This religious zealot is so devoted to the demon god Xotli that they're willing to forfeit their bodies to be temporarily possessed during combat. At which point, you transform into a sword-wielding demon and start absolutely beating ass.
Think about it: by rolling a Herald of Xotli, you're basically signing up to roleplay as a crazed devil worshipper who's just as skilled with hand-to-hand combat as ancient curses. I reckon that's pretty atypical for most RPGs.
