The five-pointed star. It is formed from the five diagonals of a pentagon.

The pentagram has been used by many groups throughout history. It was used by the early Christian church to represent the five wounds of Christ (the crown of thorns, nails in hands and feet (not counting the spear in his side, which was posthumous)). It has been used (and still is) by various pagans, Wiccans and the like as well with many variations and symbolic meanings. The inverse pentagram has been often used by Satanists (perhaps in contempt of the Christian usage, like the inverse cross, as well as its pagan implications).