Slimes that are just little orbs.
Can we please get some more representation? It's offensive!
Nah, in all seriousness, I'd like to see more adventurous designs for monsters like goblins, orks or ogres than the regular green-skinned, ugly pig men we usually get. Natural selection is a thing, and I'd like to see how they evolve for different environments. (Like a desert ork or ocean goblin.)
And no, that doesn't just mean turning them into anime girls.