I know this game is a coffin now…but really theirs really not enough diversity for tanks who are aliens. why most tanks in the roster have to be humans/demons/undead and no room for extraterrestrials? Its like the developers have some descrimination for people who like sci fi. Are they just petty that li-ming is inferior to fenix? (desintagrate vs planet cracker) Legit ive seen stronger things that can fight in medieval times using scifi technology. I bet there is a story out there that gets a little bit historical with sci fi technology like doctor who. But seriously … people in the draft are just going to complain when they state “we need a tank.” scratching artanis and dehaka off as tanks. Seriously if this community now things that bruisers arent tanks than please by all means… give us extraterrestrial tanks. Developers ya i know you think lore wise if fenix existed in the diablo series maybe li ming would be in shame. Due to the fact if diablo was weakened and he made some sort of “emergency escape” and somehow landed on mars fenix would probably “Shoot a hole into the surface of mars” while being on planet earth due to how far the range fenix is. Knowing this perspective blizzard would probably would nerf the lore just to make li ming look better. This legit is just you being annoyed of how accurate sci fi can be… I bet you are punishing your sci fi fandom of starcraft for powerscaling by not letting any exteraterrestrial tanks in game. Legit you just dont want to show the possible outcome of how extraterrestrial tanks can be as tough as doomslayer dont you. At the end of the day we dont get to see alien tanks. Because maybe its too overpowered against the likes against demons/humans/undead. Unknown inhuman technologies are the most intimidating things to perceive. All blizzard is doing is giving warcraft characters and diablo characters a night light because god forbid starcraft will make those characters hide under their blankets when a tank protoss/zerg is placed out in the field. Their too weak to face a alien tank.
Who would you propose?
My theory is they will never give us Starcraft anything for as long as people actively spread lies about the game being dead as we actively have been getting updates. But Protoss could use both a healer and tank for sure. Warcraft is kind of hogging all the healers.
Talandar would be an interesting option. Or karax (although he feels more like a support, but hey, zarya exists to prove a tank can be made support in a different game). Then, we could also have the brawl ultralisk as a playable character.
Or just give every bruiser a talent to become a tank (a 4th talent at a certain level, like 1 or 4). Give them +40% health and -40% damage, then buff/nerf the stats according to how the talent goes, for each bruiser. Some might do too well (like thrall getting % dmg later on), while others might be pretty weird (ragnaros), but we’d have lot more viable tanks.
I’m pretty sure they didn’t give us any sc tanks because there isnt many sc characters left and of the ones that are there are even less that are both extraterrestrial and would make sense as a tank, off the top of my head the remaining sc extraterrestrial characters people might actually recognize are
Judicator Aldaris, Matriarch Raszagal, Zasz, Daggoth, The Overmind and Duran from SC1 and from SC2 there’s Talandar Karax Vorazun Izsha and if you want to go really out there there’s Niadra Naktul Ulrezaj Nyon Jinarra Amon (he sucks so he doesn’t get to be in the main cast) and idk infested doctor hansen(?)
Out of all of these the only two I could really see as a tank is Ulrezaj and Talandar without some sort of really weird design choices and while i definitely wouldnt have minded them adding Talandar in as a new tank back when they were still developing I can definitely see why they did end up straying away from SC near the end of the development cycle, just not that many exciting heroes left in the IP that hadnt been done already (Terran being included adds a few more exciting ones but still)
Well i think everyone understand that this is never going to happend in a dead game, but lets dream together:
Healers: Stetmann
Tanks: Talandar, Nyon (the crazy taldarim of WoL), Maar (The hybrid, it can have a lot of shields and cc), Ulrezaj, Clolarion.
Zergs dont have “heroes” which can be used as tanks, but maye they can took an hybrid reaver and give him a name.
There’s the Zerus ones; Primal zerg | StarCraft Wiki | Fandom
So far we only have dehaka, but there’s some other 8 primal zerg to make use of. 
Dakrun and kraith (I think they have same model) are basically tanks. There’s also Zurvan, who’s kind of a tank.
Yep but they’re just common minions with a lvl up
Maybe Kraith is a good choice, but Zurvan is just a MASSIVE mutated zerling, is too big to fit through the gates lmao.
Talandar could be the protoss tank. Althought it’d be a bit confusing, as he’s just Fenix from the future.
I suppose that a generic named immortal could work…
As for the zerg… an ultralisk is what I think of when I hear about “zerg tank”, but that doesn’t sound like a compelling hero. Perhaps Dehaka could get a rework, where he can become a tank, but other than that, I can’t really think of a viable option.
An Ultralisk or the Hyperion, or Talandar.
With a title like that, it’s just asking to get a Hybrid 
A hybrid reaver hero has been listed as being under consideration for inclusion in Heroes of the Storm .[17]
The link in that citation is dead, so heres a wayback machine to a 2015 blizzcon article.
The transcript doesn’t say anything a bout a hybrid hero, but a picture of one was used while the speaker was describing the hero design process.
I actually made a hybrid reaver tank concept over on the Resurgence discord, probably would need to tweak it slightly
Edit: Finally posted it.