The Elders

The Elders are spirits made by the Gods that have proved themselves worthy by completing tasks set by their creator. After the completion of the task, a spirit is elevated to the status of Elder where they live amongst the Gods forever and are also given dominion over a part of the Gods rule the same as how a King would with his Lords as they cannot continuously watch all of there dominion.

For example Poseidon gave Auam dominion over the seas of Bleon after it had rid them of a plague placed by Nurgle

Origin
Upon the completion of the universe the Creators realised that the Gods would be unable to have a close control over all of their domain as the size was much larger than they had anticipated and the Gods were not omnipresent like the Creators. Their was a decision made that less powerful entities should be made and then judged to see if they were worthy to help control the respective God's domain.

Physicality
The Elders vary vastly in size and appearance, none look the same, even the ones that were birthed by the same Creators looked dissimilar.

Power
The Elders are the helpers of the Gods. The vastness of the universe means that the Gods have extremely large domains of control and are unable to oversee it all at the same time so the Elders oversee smaller parts under the control of the God. Their powers differ for each individual but are attached to their names and the God that they serve.