 Although not traditionally regarded as an apotropaic , mirrors have been used to ward off vampires when placed , facing outwards , on a door ( in some cultures , vampires do not have a reflection and sometimes do not cast a shadow , perhaps as a manifestation of the vampire 's lack of a soul ) . This attribute , although not universal ( the Greek vrykolakas / <unk> was capable of both reflection and shadow ) , was used by Bram Stoker in Dracula and has remained popular with subsequent authors and filmmakers . 
