Black and grey striped planarium (flatworm). I'd never seen one of these before and didn't know these are carnivorous when I took the photos. When I found out, I noticed in pic 3 & 4 it was headed for supper!
This was making its way across a path at Queen Sirikit Botanic Garden after rain. I guess the earthworms it favors to eat come to the surface when it rains & it follows suit.