The symbol used by the Man of Letters in Supernatural, this one

is called a unicrucal hexagram and resemble the symbol used by the religion Thelema

And the founder’s name is .. Aleister Crowley. Also the religions code is “Do what thou wilt shall be the whole of the Law”. In other words Free Will. (x) I don’t know if this is a coincidence, but if it is - it’s a good one.