Reflection Not Seen in a Mirror

"He throws no shadow; he make in the mirror no reflect, as again Jonathan Harker observed."

 Professor Van Helsing in Mina Harker's Journal, Chapter XVIII of Dracula by Bram Stoker

Vampires don’t reflect in mirrors. This also means that their images do not appear on film or any other device that requires a light (or heat) source to produce and image. A flame can be seen through his body. In some areas, vampires are believed not to show in photographs or to cast shadows. 

But all over Europe, there was a taboo that all mirrors that are in the same room with a corpse should be draped otherwise the spirit of the dead person might become trapped in the mirror or the living unfortunate person whose body is reflected with the body of the dead, would die soon after the dead person was buried.

A reason given for this is the old idea that the image of a person in a mirror is the soul of the person; since vampires have lost their souls they cast no reflection