Which mythological/fantasy creatures can you see as combatants?

I am in the process of writing a novel, and it involves mythological/fantasy creatures as combatants. But I'm having trouble thinking of which creatures i should showcase.
For example, I already know that I will be using angels and demons and faeries. And if you list any creatures, if you're able To, can you list what you think their powers would be? :)
I really need insight, because I want to include many creatures, but at the same time, it can be viewed as rushed and anticlimactic if I add too many since it will seem like too much is going on.
Thank you :D