1. Abraham Van Helsing from Dracula / Van Helsing

Maybe the first of this type, Abraham Van Helsing first appeared in Bram Stoker's 1897 Dracula. Professor Van Helsing demonstrates a essential knowledge to vampires which he uses to equip himself and the rest of the characters with the knowledge to defeat Dracula. 

Although the iteration pictured is from the 2004 film Van Helsing, where I'd say he's a much more modern 'monster hunter.' 

2. Buffy Summers from Buffy The Vampire Slayer 

As the opening line goes, "In every generation there is a chosen one. She alone will stand against the vampires, the demons and the forces of darkness. She is the slayer."

Buffy Summers is The Slayer, a role bestowed upon her giving her supernatural, superhero like abilities in order to combat vampires and demons. She is aided by The Watcher, Rupert Giles and The Scoobies. 

I AM ALSO ON SEASON 5 OF BUFFY NO SPOILERS PLS POR FAVOR

3. Geralt of Rivia from The Witcher. 

Geralt of Rivia is a Witcher, mutated humans specifically trained for the purpose of killing monsters. They were initially created to protect settlers of The Continent from the monsters before the land was fully settled. They have unique superhuman abilities. Witchers often offer their services in exchange for gold, much like mercenaries. 

[LOVED CHARACTER TROPE] The Monster Hunter