The Maker is the head of the common pantheon and creator of the Shards. They have not been heard from in known history.
Commonly accepted religious theory says that the Maker came upon a desolate world and began to shape it. Finding they could not do it alone, they created the Shards, taking aspects of themself and giving them divine power to shape their domain.
What happened to the Maker after creating the Shards is debated. Some scholars say the World-Eater took the opportunity to slay the Maker when they were weak, other say the Maker continued onto the next desolate world on their endless journey toward spreading life among the stars.