Ok, here’s my two, to try and get the ball rolling.
The Light and The Darkness
Two of the immortal Elder, beings from before this universe, they are engaged in an eternal war with each other. However, they did work together when their universe collapsed, creating this one from its remains. The Light brought into being all that is good in this universe, whilst the Darkness brought into being everything that is bad. They are constantly trying to gain the upper hand over the other, but they cannot fight directly, otherwise they could end all of creation, so instead they manipulate lesser species to do battle for them.
