5.9 Tortle,
Claws. Your claws are natural weapons, which you can use to make unarmed strikes. If you hit with them, you deal slashing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.
Hold Breath. You can hold your breath for up to 1 hour at a time. Tortles aren't natural swimmers, but they can remain underwater for some time before needing to come up for air.
Natural Armor. Due to your shell and the shape of your body, you are ill-suited to wearing armor. Your shell provides ample protection, however; it gives you a base AC of 17 (your Dexterity modifier doesn't affect this number). You gain no benefit from wearing armor, but if you are using a shield, you can apply the shield's bonus as normal.
Shell Defense. You can withdraw into your shell as an action. Until you emerge, you gain a +4 bonus to AC, and you have advantage on Strength and Constitution saving throws. While in your shell, you are prone, your speed is 0 and can't increase, you have disadvantage on Dexterity saving throws, you can't take reactions, and the only action you can take is a bonus action to emerge from your shell.
Survival Instinct. You gain proficiency in the Survival skill. Tortles have finely honed survival instincts.

Grappler
Source: Player's Handbook

Prerequisite: Strength 13 or higher

You've developed the skills necessary to hold your own in close-quarters grappling. You gain the following benefits:

You have advantage on attack rolls against a creature you are grappling.
You can use your action to try to pin a creature grappled by you. To do so, make another grapple check. If you succeed, you and the creature are both restrained until the grapple ends.

Strike of the Giants (UA)
Source: Unearthed Arcana 85 - Wonders of the Multiverse

You have absorbed primeval magic that gives you an echo of the might of giants. Choose one of the kinds of giants listed below. As a bonus action, you can call on the power of your giant magic to imbue your attacks with additional power. The next time you hit a target with a melee or thrown weapon attack within the next minute, the attack has an additional effect depending on the origin of your giant magic:

Hill Giant. The target takes an extra 1d6 damage of the weapon’s type. If the target is a creature, it must succeed on a Strength saving throw or be knocked prone.

The saving throw DC for these effects equals 8 + your proficiency bonus + your Strength or Constitution modifier.
You can use this bonus action a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.