Which traditions do they belong to?

Neptune belongs to the Roman Pantheon, and Poseidon to the Greek Pantheon.

Side by sideParallel across traditions

Neptune vs Poseidon

Neptune is the direct Roman equivalent, ruling the seas with the same trident and temperament.

At a glance

Neptune and Poseidon compared
	Neptune	Poseidon
Tradition	Roman Pantheon	Greek Pantheon
Domains	sea, earthquakes, horses, freshwater	sea, earthquakes, horses, storms
Symbols	trident, horse, dolphin	trident, horse, dolphin, bull
Also called	Neptunus	Neptune

Where they meet

Both are associated with sea, earthquakes, and horses.

They share symbols: trident, horse, and dolphin.

trident
horse
dolphin

Where they part

Only Neptune

Associated with freshwater.

Only Poseidon

Associated with storms.

Why they are compared

Poseidon is the direct Greek equivalent, ruling the seas with the same trident.

How each was worshipped

Neptune

Cult sites: Temple of Neptune in the Circus Flaminius; Campus Martius cult of Neptune Equester, close to the later circus and to horse-racing ground
Festivals: Neptunalia (23 July)

In the July heat Romans built leaf shelters (umbrae) and kept the Neptunalia as a thirsty outdoor feast. Neptune's Roman life is water, horses, and the fear of drought more than a Greek-style sea epic. State sacrifice used a bull.

Poseidon

Cult sites: Sanctuary of Poseidon at Isthmia; Temple of Poseidon at Sounion; Onchestos in Boeotia
Festivals: Isthmian Games; Posideia

Horses, earthquakes, and the drowned coast are his working signs. Isthmia held games under his name. A bull often went to the sea. Inland Boeotia kept him as a horse god, not only a sailor's patron.

The two figures

Roman Pantheon

Neptune

God of the sea, earthquakes, and horses. Brother of Jupiter and Pluto, ruler of all waters. Also associated with freshwater springs and patronage of horse racing.

Neptune rules waters in Roman religion, including the sea the poets borrowed from Greek Poseidon. Older Italian cult, though, ties him as closely to freshwater and to horses as to the open Mediterranean. The **Neptunalia** in July was a festival of midsummer drought, when Romans built leaf shelters and remembered the god who could give or withhold water.

Read the full Neptune entry

Greek Pantheon

Poseidon

God of the sea, earthquakes, and horses. Brother of Zeus and Hades, ruler of the oceans and all waters.

Poseidon rules the vast oceans, earthquakes ("Earth-Shaker"), and horses. He is a moody and tempestuous god, much like the sea itself. Sailors prayed to him for safe passage, often sacrificing horses or bulls to appease his wrath.

Read the full Poseidon entry

About this comparison

Comparisons pair figures that play a similar role across traditions, or that the myths connect within one. A shared role does not, by itself, establish a shared origin.