Delphinus, the dolphin:

A small but ancient constellation that is easily located in the night sky. Delphinus represents the dolphin that helped the sea god Poseidon win the heart of his wife, the mermaid Amphitrite. In another story Delphinus is the dolphin that helped the musician Arion escape from sailors who attempted to throw him overboard and steal his belongings. The god Apollo was so moved by Arion's music, he sent the dolphin to carry him to the shore. The constellation can be found to the east of the bright star Altair in the constellation of Aquila, the eagle.