“Slender Man” (** out of four) was a thin horror thriller (no pun intended) set in a small town in Massachusetts in which a group of friends (Joey King, Julia Gondani Telles, Jaz Sinclair and others) set out to prove that an internet horror phenomenon known as Slender Man doesn’t exist until one of them goes missing and they start to realize there may be more to his legend than meets the eye. Well-made and well-acted horror story has just one main problem: it isn’t very scary. The more we learn about the title character, the hokier he seems (and movie gets). Based on an actual 2008 internet meme by Victor Surge which is where it should have stayed.