What mythical beings are ociated with order, chaos and balance?

The entity that sprang to mind was Cernounus of the Celtic Pantheon. He is the god of balance between the forces of Hoarding and Generosity. His iconography is such that it is very obvious that is at least part of his job. He is also the god of borders and of the in-between lands such as marshes and bogs as well as clan boundaries. He strives to keep a balance between states at all times.