For the river, see Achelous River

In Greek mythology, Achelous (Greek: Αχελώος), was the patron deity of the river by the same name, which is the largest river of Greece, and thus the chief of all river deities, every river having its own river spirit. His name translates as "he who washes away care". He was the eldest child of Oceanus and Tethys. Achelous was a suitor for Deianeira, daughter of Oeneus king of Calydon, but was defeated by Heracles, who wed her himself. Sophocles pictures a mortal woman's terror at being courted by a chthonic river god:

'My suitor was the river Achelóüs,

who took three forms to ask me of my father:

a rambling bull once, then a writhing snake

of gleaming colors, then again a man

with ox-like face: and from his beard's dark shadows

stream upon stream of water tumbled down.

Such was my suitor.' (Sophocles, Trachiniae)

The sacred bull the serpent and the Minotaur are all creatures associated with the Earth Goddess Gaia. Achelous was also portrayed as a gray-haired old man with horns. He was also considered a storm-god. He was sometimes the father of the Sirens by Terpsichore.

When Achelous was defeated, Heracles took one of his horns, and Achelous had to trade the goat horn of Amalthea to get it back. Heracles gave it to the Naiads, who transformed it into the cornucopia.