Achelous

n. long river in Greece; (Greek Mythology) god of the river by the same name

In Greek mythology, Achelous (English /ækə'loʊəs/ Greek: ) was the patron deity of the "silver-swirling" Acheloos River, 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".
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[Greek] In Greek mythology, Achelous is the deity of the river of that name, and ruler of all rivers. He is the eldest son of Oceanus and Tethys. He fought with Heracles for Deianira, a Greek princess. Despite assuming many forms, among which that of a bull, Achelous was eventually vanquished. Heracles broke off one of his horns and nymphs fashioned it into the Cornucopia ("horn of plenty"). Achelous is usually depicted as a bull with the torso of a man and a bearded face (common for river gods, especially on coins), but also as an old, grey man with horns. (Ovid VIII, 547; IX, 1).