I'm trying to build the optimal tank

[Klorox]

I'm talking about a character that can take a ton of physical punishment, and that can control the field of battle (possibly draw attacks away from the glass characters in the party).

I was originally thinking of a barbarian/warlock with the shield master feat, but I wanted to open the idea up for other things. Perhaps a polearm master type fighter or barbarian? Perhaps something quite different.

I look forward to your input guys!

[bid]

Barbarogue.

Swashbuckler 9 is the only true aggro control. Uncanny dodge and evasion are great tanking tools.

[Goober4473]

Barbarogue.

Swashbuckler 9 is the only true aggro control. Uncanny dodge and evasion are great tanking tools.

Plus rogue works well with the shield bash, since it's an easy way to get advantage to sneak attack, and it also combos very well with Sentinel, a very good tank feat, since sneak attack can be used once per turn rather than per round. This means the "punishment" mechanic is actually quite punishing, making enemies think twice about attacking your allies. And when they attack you instead, you've got Uncanny Dodge, which stacks with barbarian resistance since it halves the damage rather than giving you resistance to it.

Just make sure to use a finesse weapon, but use Strength to attack with it. Shield + rapier would be the standard.

[ES Curse]

Battlemaster Fighter with control type maneuvers (Goading Attack, Trip Attack) and the Defense Fighting style. Use a polearm for range or sword & board for better AC. Take the Sentinel feat to keep them where you want them.

[Coidzor]

Oath of the Crown is almost really good for that, at least for its 3rd level ability.

If you have lots of encounters at long ranges but with the ability for your melee to close or your ranged to withdraw then it can prove handy, but is useless in encounters that take place solely inside of a 60 by 60 area.

[Waffle_Iron]

Plus rogue works well with the shield bash, since it's an easy way to get advantage to sneak attack, and it also combos very well with Sentinel, a very good tank feat, since sneak attack can be used once per turn rather than per round. This means the "punishment" mechanic is actually quite punishing, making enemies think twice about attacking your allies. And when they attack you instead, you've got Uncanny Dodge, which stacks with barbarian resistance since it halves the damage rather than giving you resistance to it.

Just make sure to use a finesse weapon, but use Strength to attack with it. Shield + rapier would be the standard.

I went thief/wolf totem. Wolf means I grant advantage to my allies, making the party better. Thief means I can change tactics and be opportunistic.

I took sentinel, which is great for the reasons you outlined.

I use a scimitar and dagger, though I could use two scimitars if I wanted. Mostly I use scimitar and open hand, for grappling. Expertise in stealth and athletics makes for a effective combo, considering cunning action.

I may not hit as hard as the paladin/sorc, but the team knows I can drag them out of a fire. Sometimes literally.

[Specter]

I'm thinking Barbarian with all the Bear Totem features, along with Sentinel. Giving disadvantage against anyone other than yourself is dandy. Also convince the caster to cast Mirror Image on you.

[gfishfunk]

Really: depends on party make-up.

Shield Master is great if you have a highly melee oriented party but becomes less useful if you have a lot of ranged folks. Grappling is fantastic if you are looking at controlling one major enemy. There are a lot of great paladin spells (smite spells, not smiting using spell slots) that impose restrictions on enemies, and the spell Command makes a great and simple control spell.

The best at taking punishment would be a totem barbarian - bear + sentinel if you have a lot of long distance teammates, shield bash + bear totem if you have a decent mix, and grappler + wolf totem if you have all melee would be my preference.