Fighter
The Fighter is one of the basic classes in almost every RPG system ever made.
Class role
The fighter's primary role is serving as a meat shield and smashing (slicing, piercing, whatever) things both inanimate, living and undead (as well as any others you can possibly think of). Fighters are also traditionally good at physical activities like jumping, riding animals, balancing, and drowning under the weight of their own armor, however given their tiny number of skill points they can typically only be good at one or two skills while the rest languish.
Dungeons and Dragons
In DnD the Fighter class has existed since the very first incarnations(Then called "fighting-man"). In 3.x the fighter is a meatshield that gets loads of Feats making it the only class that can take more than one full-size feat tree such as archery and weapon specialization. This is "balanced" by taking away virtually all skill use ability which means that the Fighter (usually encased in heavy armor) would have difficulty jumping across a 5-foot hole if the DM made them roll for it.
Fighter was, for some unknown reason, considered seriously underpowered in D&D 3.5 up to the point of people saying "Yeah, sure, you can join; we could use a fighter. Just don't use any splatbooks." This was a polite way of refusing a request upon joining the party.
In 4th edition the Fighter is a "Defender" basically meaning that it's sole purpose is to serve as a meatshield and prevent the enemies from getting close to the squishies behind them while the squishies proceed to demolish the enemies.