The Hunter - a Class for Lamentations of the Flame Princess (or other Old-School Fantasy games)

A simple martial class that does a decent job representing anything from a Solomon Kane style witch-hunter, to a dedicated dragon-slayer or duelist.

The Hunter

Solomon Kane by Draldede

XP, Saves, and HP as a fighter. Uses fighter combat options (but not ascending AB). 

Where the fighter is an unmatched engine of slaughter, the Hunter is specialist, forsaking general combat prowess in exchange for absolute mastery against their chosen prey.

Prey:
Hunters begin with 3 points to spend on their choice of prey, a type of enemy against which they get a number of bonuses. Good prey categories include: Humans, Dwarves, Elves, Spirits/Spectres, Demons, Unintelligent Dead, Vampires, Magic-Users, Were-things, and so on.

Hunters can only choose a type of prey after they have spent some time studying it and have fought it in combat. On each level after the first, they gain 2 more points that they can spend on new or existing categories of prey, though the original conditions apply. To go from Vampires 1 to Vampires 2, you have to find, study and fight another vampire. The maximum amount of points they can assign to a given category of prey is equal to their current level.

Whenever they are making rolls against an enemy of a type designated as prey, they gain their ranks as a bonus to any ability, saves, attacks, or damage rolls against them. If a character had Sorcerers 3, they would gain a +3 to attack and damage rolls against them, saves against them, or any ability rolls that are directly concerning or in opposition to them.

The hunter can definitely outclass a fighter against the very specific enemies they have dedicated themselves to, but the fighter is definitely the more powerful opponent overall. This is particularly true if they have started to spread themselves out and have less than their maximum bonus at any particular level.
If you try to bring this into some other game, be sure to note that in LotFP only fighters gain attack bonuses normally. You may want to tone the prey bonuses down for games where everyone advances in their To Hit.