Once in Hollywood, we saw a guy who seemed to be costumed as a Martian.  Not a BEM, though.  He was about seven feet tall, bald, extremely thin, and was clad entirely in skin-tight black leather (or a leather substitute).  He also seemed to have a hard time breathing; he stopped every few feet and rested on a low concrete-block wall, panting heavily.  Of course, it was an extremely hot day.  But still, he looked to us like an alien from a lower-gravity planet with a different mix of oxygen in its atmosphere.  I think it was a coincidence that this was at Franklin and Canyon, a block west of Bronson, and about a half-mile from the Caverns, which have hosted several varieties of alien.... (I have this guy on movie film.)