Sylvain White Director Joey King Wren Actor Julia Goldani Telles Hallie Actor Jaz Sinclair Chloe Actor Annalise Basso Katie Actor Alex Fitzalan Tom Actor Taylor Richardson Lizzie Actor Javier Botet Slender Man Actor Jessica Blank Hallie's Mother Actor Michael Reilly Burke Hallie's Dad Actor Kevin Chapman Mr. Jensen Actor Miguel Nascimento Kyle Actor Eddie Frateschi Biology Teacher Actor Oscar Wahlberg Boy With Glasses Actor Danny Beaton Burly Kid Actor Gabrielle Lorthe Cheerleader Actor Marc Carver Doctor Actor Kris Sidberry Librarian Actor Angela Hope Smith Nurse Actor Michael Tow Calculus Teacher Actor Damon D'Amico Jr. Student Actor Yohanna Perez Student Actor Timothy Brierley Tour Guide Actor David Birke Screenwriter Bradley J. Fischer Producer James Vanderbilt Producer William Sherak Producer Robyn Meisinger Producer Sarah Snow Producer Louis Sallerson Executive Producer Tracey Nyberg Executive Producer Adam Kolbrenner Executive Producer Ryan H. Cunningham Executive Producer Glenn S. Gainor Executive Producer Luca Del Puppo Cinematographer Jake York Film Editing Ramin Djawadi Original Music Brandon Campbell Original Music Jeremy Woodward Production Design Kim Leoleis Set Decoration Deborah Newhall Costume Design Nancy Nayor Casting