Neptune's greek name was...

The Greek god Neptune is known as Poseidon in Greek mythology. Poseidon was the god of the sea, rivers, earthquakes, and horses, and was one of the twelve Olympian gods. He was often depicted as a powerful and bearded deity, wielding a trident and riding a chariot pulled by mythical sea creatures. Poseidon played a significant role in Greek mythology, being associated with marine life, navigation, and the control of natural forces, which aligns with the domain and attributes commonly associated with Neptune in Roman mythology.