We only have one troll hero, Zul’jin.
We don’t even have troll skins for other heroes.
Orcs, elves, human have plenty of heroes and themed skins for other heroes.
There are also plenty of possible troll heroes, Vol’jin, bwonsamdi and talanji to name a few.
There are also a lot of possible skins for many of the current heroes.
For example:
Nazeebo - Troll Hexer
Falstad - Troll bat rider
Deckard - Troll Witch doctor
Cassia - Troll headhunter
Zeratul - Troll Shadow hunter
Butcher - Dire troll