Something to keep in mind when exploring Celtic Gods and Goddesses family trees is the people who called themselves or where given the name Celtic in later years come from a wide variety of places stretching from Turkey to Germany and onto the what is now known as the British Isles (Wales, Ireland, England, and Scotland). Each of these tribes had a few of the same deities but known y different names and some of the Celtic deities were now only in a specific region. So I will present to you here a few of the better know pantheons and give you the links to where I found the pictures of the family trees so you can explore further on your own.
Here is one version of the Celtic Deity family tree:
Here is a link to images on bing.com of other Celtic deity family trees for you to check out: Celtic Deity Family Trees