All of these can be built with more damage items to deal more damage but they all do decently well with only one damage item or even being full tank (kinda like Hecarim).
Reksai is a great champion and can be built hybrid. If you want some damage you can build. Cinderhulk, Titanic Hydra, MAW, Randuins omen, Merc treads and GA.
Try out zac with magic pen runes and liandry's torment then full tank with thunderlord masteries you will one shot enemy adc and you are basically immortal.
Nice mobility + Nice CC, you just need to play on vocal with your friends, so your allies are not surprised by your ganks and they can push while you are using your passive
I main Shyvanna and Rammus in JG and they are great tanks! They hit really hard and can take a good hit just by building armor. I highly and I mean HIGHLY recommend them both!
I am not really a jg player, but I am aware these guys are decent jg and can be tanky. Amumu (has multiple stuns and aoe), Rammus (can be fast), Trundle (tanky and can apply slows). Everyone else was previously mentioned that I could think of.
Udyr, Xin Zhao, Chogath, Ekko if you build him tank, and Skarner is a under rated tank jg that does massive damage. He isn't used as much, but if you play within his circles that give him that movespeed and attack speed bonus. Jungle camps get cleared really fast, and he does great damage. J4, Olaf, and Shyvanna are also great picks, Olaf deals true damage with his E and just gets stronger the lower he gets. Shyvanna is honestly just a beast in the jg, and J4 does great damage, and you can build him tank
tl;dr:
Vi, Elise, Gragas, Volibear, Skarner, Zac
In order from more damage -> more tanky
All of these can be built with more damage items to deal more damage but they all do decently well with only one damage item or even being full tank (kinda like Hecarim).
Nice mobility + Nice CC, you just need to play on vocal with your friends, so your allies are not surprised by your ganks and they can push while you are using your passive