What actors and actresses appeared in Slenderman Attack - 2013?

There is no film or movie titled "Slenderman Attack - 2013." It is likely that you are thinking of the 2016 documentary film "Beware the Slenderman," which explores the 2014 stabbing of a 12-year-old girl in Wisconsin by two 12-year-old girls who claimed they were influenced by the Slender Man internet meme.

"Beware the Slenderman" is a documentary, meaning it features real people, not actors.