Poseidon

Poseidon was the Olympian sea god, and also the deity of rivers, horses, earthquakes, floods and droughts. For sea voyagers, he could either send storms or grant safe travels.
 
Right: Poseidon image of hippocamps from Bardo Museum, theoi

In myth, he contested with Athena to achieve dominion over the city of Athens, He also produced the first horse. In his undersea kingdom at Aegae, he stabled his brazen-hoofed horses with their golden manes. A three pointed trident symbolized his power.

Poseidon was the father of Polyphemus the Cyclops and avenged his son when Odysseus blinded him.

He also helped Apollo build the walls of Troy, and when payment as promised was not forthcoming, sent a monster to devour the daughter of Laomedon, who had hired them. The girl was saved by Hercules, who killed it.