Hera
Heracles is the stepson and enemy of Hera. Hera discovered that her husband, Zeus had an affair with a mortal women named Alcmene and she became extremely jealous at the mortal woman. Hera used all the power she had to prevent Alcmene from giving birth to Heracles. When Alcmene was about to give birth to Heracles, Hera requested that Zeus swore an oath and declare upon all the other Gods that the descendant of Perseus will be born on that day and the child will rule eveything around him. Then Hera descended from Olympus to Argos and cause the wife of  Sthenelus, son of Perseus to gave birth to Eurystheus after only seven months while Hera tried to prevent Alcmene into giving birth to Heracles by sending her daughter Eileithyia and witches. This cause the fullfilment of Zeus' oath in that it was Eurystheus instead of Heracles. Hera continues her wrath on Heracles while he was still an infant. She send two poisonous snakes to Heracles to kill him in his cradle. Heracles throttled the snake with his bare hands and the nurse saw him playing with the dead snake as if they were a child's toy. Hera continues to torture her stepson throughout his life.