Poseidon (Greek: Ποσειδῶν) is the god of the sea, earthquakes, storms and horses in ancient Greek religion and myth, one of the Twelve Olympians. The son of Kronos and Rhea and the elder brother of Zeus, Poseidon was generally regarded as an ill-tempered being, with his mood serving as a reflection of the state of his realm, as he was thought to conjure up violent storms at sea when angered. While he was married to the goddess Amphitrite, one of the Nereids, like his brother Zeus, Poseidon had a number of affairs with other goddesses and mortal woman, siring such heroes as Theseus and Bellerophon. Lord of the waters, Poseidon served as both patron and protector of both sailors and seafarers, who would pray to him for safe passage across the sea. Poseidon was often regarded as the “Father of Horses,” as they were thought to be his creations. He was additionally the chief deity and patron of the city of Corinth, whereupon the Isthmian Games were held every other four years in his honor. Otherwise known as the Earth-Shaker (Greek: Εννοσιγαιος), Poseidon was thought to be the cause of such disasters, striking the Earth with his trident (a three-pronged spear) whenever he was particularly enraged. The god's symbol was his trident and the bull, horse and dolphin were his sacred animals. The god Neptune is his Roman equivalent.