Inspiration: Kill Bill, Wuxia films, and spaghetti westerns
Experience: As Elf
Saving Throws: As Elf
Unarmed Attack Bonus: A monk has a bonus on all unarmed attacks. This is one half, rounded up, of the bonus a fighter of the same level has. Monks deal 1d6 damage with their bare fists.
Uncanny Presence: Due to a monk coming from far away and being raised in a different culture, something about them always seems off... Enemies facing a monk take a -2 penalty on their morale rolls.
Brutal Assault: Whenever a monk delivers the final blow to an opponent, their player can narrate exactly how it happened.
Defensive Stance: Whenever a monk does not attack in a round, they add their unarmed attack bonus to their Armor Class.
"He somersaults over the guard effortlessly before shrieking like a raptor and pulling out the guard's heart from his chest with his bare hand! As the guard slowly crumples over, the monk takes a bite from the still beating heart before dropping it on the ground."
In my opinion, this is a way to get the senseless overkill shown in many martial arts flicks without having to make the character actually overpowered, as well as giving the player a creative outlet. The monk is a lone stranger from far away, exiled from their home land. No one has seen someone else capable of such sheer violence and the monk will not teach anyone.