Monk

The Monk class, as it appeared in the D&D 3rd edition Player's Handbook.

A monk is a member of a monastic order who has taken vows to eschew the material world for a more "spiritual" path. In Europe this usually refers to a Catholic priest devoted to living a humble life separate from normal society in a monastery. In Asia, it's a Buddhist priest; in Islam it would be a sufi or dervish.

The medieval European monk is more in line with the Priest/Cleric class, but the Irish Catholic monks were highly proficient in drunken boxing. Despite this fantasy gaming's usually setting in middle-ages Europe, the term "monk" usually refers to the Asian version of a monastery dweller, specifically from the Shaolin temples of northern China, who were self-organized into a legendary militia to defend the temple against barbarian Mongol raiders. This is thanks to Dungeons & Dragons, which introduced the Monk class as a martial arts expert, much in line with kung-fu movies where people dance on bamboo leaves while beating each other up with super-fast punches and kicks.

With the proper feats and items, you can turn any D&D Monk into a veritable machine of death, destruction, and holy Jesus fucking Christ fists (3rd Ed Hint: The tripping line of feats + spiked chain) but that's only after you've gotten over the horrible hump of single-digit levels, and you will still be the fifth wheel in a party that has a Cleric or Wizard. You're better off using a Barbarian, Bard, Ranger, Swordsage... pretty much any other class if you're starting from level 1.

Advanced Dungeons & Dragons

The monk class seems to be an afterthought, even appearing last in the list of classes instead of in alphabetical order. The monk class required four ability score minimums, started with an average of (2d4 +1 CON bonus) 6 hit points and COULD NOT WEAR ARMOR... but had a natural AC of 9, whoop-de-doo. The oh-so-awesome unarmed combat licked taint, since even a magic-user could do more damage with darts, and do it at range. However, the powers they got at higher levels were over the top, with immunity to disease, poisons and eventually aging, AC that was better than plate while they're still naked, fists that counted as magic weapons for hitting ghosts and undead, nigh-invulnerability to falling damage, and the quivering palm attack that could make your target's heart stop immediately (or days later if you felt like it.)

Also, their fists went from taint-licking suck to the only d20 weapons in the game.

Dungeons & Dragons 3rd Edition

Monks: You're doing it right.

The monk was revamped and brought into line with the rest of the melee classes, but still treated as a weeaboo kung-fu master in a world of Merlins and knights. The power curve was more gradual and didn't start with suck, though it most certainly ended with it. They also got the "weapon proficiency: exotic" so they could use weird weeaboo horse-stickers and nunchucks, and their abilities were associated with this quasi-magic stuff called "ki." They're a tier 5 class, meaning that they are in the same pit of shame as the Healer, Soulknife, and unoptimized fighter. Why, you ask? Because anything they can do can be done with magic items that they probably won't even be able to use, they do shit for damage, their armor class is shit, and they can't hit shit (3/4ths BAB.) Oh, and they're the damn poster boys for MAD (srsly, just look at that page.)

Also, they're not proficient with unarmed strikes. Seriously. Look it up.

Dungeons & Dragons 4e

The first Monks were an errata from Wizards, suggesting you could have a Monk class if you used a dual-wield Ranger build with a few changes to use "fists" as the dual weapon.

Monks were published in the PHB3, and they are a Psionic Striker. They are built to bounce around the battlemap with every strike, shifting and teleporting all over the damn place like a rubber ball fired out of a shotgun. They also get a lot more fantastical fighting game/anime inspired attacks, like turning invisble or throwing hadokens. Monks use ki focuses to power their abilities, meaning they can get attack bonuses regardless of the weapon they are wielding at the time. They also have "disciplines", which confer defense bonuses and determine the type of Flurry of Blows they have. Instead of Flurry of Blows being multiple attacks, it is a second attack as a free action after the first that doesn't require an attack roll and does set damage (so a melee magic missile without the 'force' keyword). As your level progresses, you can do more damage with the flurry and target more people.

Monks also have some abilities that are bound to be errata'd soon, including one that when read as written results in one of your targets exploding into a pile of gibs, and the other possibly gibbing too, but at the least will be near-dead.

Pathfinder

Got a number of buffs and tricks to try to avoid some of the problems listed above, can now equip Cestus weapons to add magical effects to their fists, and they can get a positively retarded amount of attacks, though their MAD issues are still... well, less of an issue, but still present. They get animal fighting styles ranging from classical, historical ones such as tiger and mantis, to djinni, kobold and even stranger things; lots of weird chinese weapons such as monk's spades, nine section whips and so on; "vows", which are self imposed conditions as never talking or try to solve everything peacefully and fight defensively or tell only the truth, and if you do not break'em you gain bonus Ki points; and a lot of archetypes, that either make them into "single class multiclasses" (the sensei is a monk with bardic performances, the qiggong monk can duplicate the effect of spells burning ki points, the sohei is essentially a monk-fighter-ranger-whatever, he is on horseback mostly), which is in line with the "20 level in a single class" paizo policy, or are awesome and hilarious (the drunken monk generates ki points from alcohol, the tetori is a Los Tiburon kind of wrestler).

Many people find the Zen Archer to be pretty broken, but most of those same people are perfectly okay with a Wizard or CoDzilla and willing to ignore the high cost of paying for your own silver/cold iron/alignment/adamantine ammunition.

If, for some insane reason, you want to play a Medieval European "monk", that's a Cleric archetype called the Cloistered Cleric, which trades a buttload of spellcasting and combat prowess for extra prowess as a knowledge skill monkey (and therefore, is useless).

The Classes of Pathfinder 1st Edition
Core Classes:	Barbarian - Bard - Cleric - Druid - Fighter - Monk Paladin - Ranger - Rogue - Sorcerer - Wizard
Advanced Player's Guide:	Alchemist - Antipaladin - Cavalier Inquisitor - Oracle - Summoner - Witch
Advanced Class Guide:	Arcanist - Bloodrager - Brawler - Hunter - Investigator Shaman - Skald - Slayer - Swashbuckler - Warpriest
Occult Adventures:	Kineticist - Medium - Mesmerist Occultist - Psychic - Spiritualist
Ultimate X:	Gunslinger - Magus - Ninja - Samurai - Shifter - Vigilante

Dungeons & Dragons 5th Edition

Their MAD has been pretty much fixed thanks to their fists using Dex for damage instead of Str. They also deal a D4 of damage with their fists until 5th level (But they can do higher damage using Monk weapons such as the quarterstaff), but they also have two attacks per round, so it balances out. Monks in 5e must choose at 3rd level between 1: being a classic D&D 3e monk with Quivering Palm, Wholeness of Body, and a ki-powered Sanctuary spell, 2: a stealthy "ninja" monk that uses ki to be invisible in darkness and sneak around, or 3: an "elemental" monk who uses Ki to cast certain spells (like a Psion), with an Avatar: The Last Airbender-type theme.

Warhammer Fantasy

Monk was one of the career choices during character generation, mentioned in the splatbook Tome of Salvation. This is the European style monk, living a ascetic lifestyle in a setting where life is nasty, brutish and short.

• Stat Bonuses: WS+5, S+5, T+5, Ag+10, Int+25, WP+15, Fel+15, W+4
• Acquirable Skills: Academic Knowledge (Theology), Academic Knowledge x2 , Animal Care, Common Knowledge x2, Heal, Perception, Read/Write, Speak Arcane Language (Magick), Speak Language (Classical), Speak Language x2.
• Acquirable Talents: Linguistics.
• Gear: Prayer Book, Religious Symbol, Robes, Writing Kit.
• Previous careers can be: Friar, Initiate, Physician, Scholar, Scribe, Student
• Next careers can be: Abbot, Apprentice Witch, Cantor, Cult Acolyte of Khorne, Cult Acolyte of Nurgle, Cult Acolyte of Slaanesh, Cult Acolyte of Tzeentch, Demagogue, Friar, Physician, Pilgrim, Priest, Scholar, Slave, Steppes Nomad, Steward, Thrall, Wise Woman, Zealot