Which race would you add to Heroes?

Well, if the dwarves in the elven castle are out of place, then what are the centaurs doing there?! Half-human, half-horse creatures have nothing to do with elves, but it would be boring without them, just like without dwarves.
And why not create a race of aliens, for example? It would be interesting to see how vampires drink green blood and curse about the incompatibility.