Scientific name -- Crocodylus Apophis
Size -- Varies
Diet -- Mid-Sized Mammals, Snakes, Birds, Humans

Every morning Ra, the sun god, was reborn.  Every evening he died.  During the night, Ra's body made a journey through the watery underworld from the western horizon to the eastern horizon.  Every night, an extremely large, evil, snake attempted to destroy Ra's body and prevent the rising of the sun.  This snake was called Apep, or Apophis by the Greeks.  Ra had variuos deities ride on his funeral barge to protect his body from this terrifying beast.  If Apep succeeded, the sun would not rise, which is an ancient explanation for solar eclipses.