2 Kings 11
After King Ahaziah of Judah was killed, his mother Athaliah went nuts: "When Athaliah the mother of Ahaziah saw that her son was dead, she proceeded to destroy the whole royal family." (vs 1) Can you imagine this? A grandmother setting out to kill all of her grandchildren? The children of Ahaziah were heirs to the throne, but apparently, Athaliah decided that she should sit on the throne. And she did. She became the only queen of Judah.