Supernatural creatures that can answer prayers but aren’t Gods, Saints, or Demon Princes are known as Spirits. They are animals, plants, landmarks, or natural events that have gained sentience and a significant (but still short of Godhood) level of metaphysical power and seek to either expand their power (often by preying on nearby mortals) or to maintain the status quo of their environment.
Spirits can answer prayers of those who worship or serve them, but they are more limited in what they can do in the mortal world than the true Gods or Old Gods. There may be opportunities in play to become a Mystic of a Spirit, but doing so will result in a much more limited spell and ritual list for you to learn than if you were to be a follower of one of the five True Gods.