Lotan
Yam-nahar is the 7 headed sea serpent-god or dragon-god of Canaanite myths. He is also called: Yam, "Sir Sea", "Sir Stream", Yaw, Yamu, "Prince Sea", "Judge River", Tannin, Primeval Serpent, Lotan, Crooked Serpent, Sea Monster, close-coiling One, Tyrant of Seven Heads
He represents floods, oceans, and winter. El made him king. He lives in a palace in the sea. His followers may be dragons, serpents, and the Leviathan. He fights with Baal, and is finally destroyed by Baal.
a source: Poem of Baal