he wears a smile; everybody run

[When we were shooting the pilot for Twin Peaks, we had a set dresser named Frank Silva.  Frank was never destined to be in Twin Peaks, never in a million years.  But we were shooting in Laura Palmer's home and Frank was moving some furniture around in her room[...]And this picture came to me of Frank in the room.  I went running in and I asked Frank, "Are you an actor?" And he said, "Well, yes, I happen to be," because everyone in L.A. is an actor.  And maybe everyone in the world.  So I said, "Frank, you're going to be in this scene."
   We did a pan shot of the room, twice without Frank and then one time with Frank frozen at the base of the bed.  But I didn't know what it was for or what it meant.
   That evening, we went downstairs and we were shooting Laura Palmer's mother on the couch.  She was lying there in sadness and torment.  Suddenly she sees something in her mind's eye and bolts upright, screaming.  Sean, the camera operator, had to turn the wheels and follow her face as she bolted up.  And it looked to me like he did a perfect job.  So I said, "Cut - perfect, beautiful!"  And Sean said, "No, no, no.  It's not."
  "What is it?"
  "There was someone reflected in the mirror."
  "Who was reflected in the mirror?"
  "Frank was reflected in the mirror."]

 - David Lynch, in Catching the Big Fish, on how the (terrifying and nightmare-inducing) character of Bob came to be