Brawler

While the fighter may be the master of weapons, you were born with the only weapons you'll ever need. Spot weaknesses in your opponents defenses, and deliver lethal strikes with your fists. Use your enemy's offense against them, punish people foolish enough to be grabbed by you, and fight through the pain. 

Bare Knuckle Specialist

Beginning when you choose this archetype at 3rd level, you gain access to the unarmed fighting style. If you already have it, you gain access to the thrown weapon fighting style instead.

Starting at level 7, you may deal an additional 1d4 of bludgeoning damage at the start of your turn to a creature you have grappled. This bonus increases to 2d4 at level 10, and 3d4 at level 15.

Thrown Weapon Fighting

You can draw a weapon that has the thrown property as part of the attack you make with the weapon.

In addition, when you hit with a ranged attack using a thrown weapon, you gain a +2 bonus to the damage roll.

Unarmed Fighting

Your unarmed strikes can deal bludgeoning damage equal to 1d6 + your Strength modifier on a hit. If you aren’t wielding any weapons or a shield when you make the attack roll, the d6 becomes a d8.

At the start of each of your turns, you can deal 1d4 bludgeoning damage to one creature grappled by you.

Cross Counter

Starting when you select this archetype at 3rd level, you are a master of using your opponent's offense against them. When you are struck with a melee attack, you may use your reaction to make an unarmed strike against them. On a hit, the target is knocked prone and you may attempt to grapple them if you are not already grappling a creature. You may use this ability a number of times per long rest equal to your proficiency bonus.

Aim For The Weak Spot

Starting at 7th level, you've learned to find the weak spots in your enemies defenses. You gain a +1 bonus to attack and damage rolls of your unarmed strikes, and your attacks now count as magical for purposes of overcoming resistances.

Tough It Out

You don't learn to fist fight if you can't take a hit. Starting at 10th level, as a bonus action, you may expend a hit die, roll it, and restore hit points equal to the number rolled plus your CON modifier. You may do this a number of times equal to your proficiency bonus per long rest. 

In addition, your bonus to attack and damage rolls on your unarmed strikes increases to 2.

Master Pugilist

Starting at 15th level, your unarmed strikes score a critical hit on a roll of 19–20. In addition, the bonus to attacks and damage on your unarmed strikes now increases to 3.

Fight Until The Bell Rings

At 18th level, you can continue fighting even after your hit points reach zero. You do not fall unconscious, and may continue to act as normally, though you do make death saves as normal. If you are hit with an attack, you automatically fail a death save. If you are critically hit, you fail two death saves.