A lady temptress and the counterpart to an Incubus. She is thought to seek sexual intercourse with sleeping men. The succubus (as well as Incubus) were thought to be fallen angels, looking foir revenge. Demons, witches and deformed children were the supposed outcome of intercourse with a succubus (incubus).
If you wake at night with excrutiating pain and a very large boner, you have probably been in contact with a Succubus.