My friend Marilen is fascinated with this one. It is the story of "Irene of Athens" who ruled Constantinople, in her son's stead, from 753-803. What makes this interesting is the fact that Irene actually had her son "blinded" in an effort to make herself ruler.
She was married to LEO IV, who ruled for five years, and was under Irene's thumb. She controlled policy and warfare, and it was under suspicious circumstances (it is very probable that Irene had him killed) that LEO IV met his death.
What is not suspicious is the way in which Irene had her own son killed.
Constantine IV would have been Emperor. He was only six when his father died. Growing up in the royal court he proved to be frivolous, flirtatious, and perhaps scandalous in his escapades with young women. In Constantinople, no "deformed" or "maimed" ruler was able to take control -- and Irene used this to her full advantage. Her son was seized and then mutilated when his captors took red-hot irons to his eyes. It was not something he would survive. For days he lingered in pain before finally succumbing to death.
Irene ruled for fifty years... but her rule was never accepted. Despite the ongoing "Iconoclasm" (still raging between those who supported paintings and idols within the Church, and those who did not) it was, in reality, Irene's callousness and cruellness which people could not accept. She was called Irene "The Terrible" and Irene "The Murderer" for the death of her son.