Marble Hornets

Marble Hornets is an American found footage web series created by Troy Wagner, Joseph DeLage, and Tim Sutton. It is a pseudo-documentary based on the Slender Man online mythos. The first video posted to YouTube was on June 20, 2009, 10 days after Eric Knudsen made the original images of Slender Man on the Something Awful forums. It follows film student Jay Merrick (Wagner) as he investigates what happened to the student film Marble Hornets, abandoned by its director Alex Kralie (DeLage) after encountering the Slender Man (called "the Operator").

There are 92 episodes on the Marble Hornets channel, with accompanying videos from a diegetic side-channel, totheark. As of late 2025, it had over 700,000 subscribers and received 125 million views. It also established the Slender Man symbol, which has since appeared in many other stories featuring the character. It would go on to inspire multiple web series in the same style as Marble Hornets, including EverymanHYBRID and TribeTwelve, with these types of web series given the nickname "The Slenderverse". The reception for Marble Hornets has been mostly positive from critics, journalist, and fans.

Marble Hornets spawned three spinoff sequel series entitled Clear Lakes 44, ECKVA, and Marble Hornets: Rosswood, the latter of which is also hosted on the Marble Hornets channel. In 2012, Blue Isle Studios announced its partnership with the Marble Hornets team to help write the script for the video game Slender: The Arrival. In 2015, a film adaptation entitled Always Watching: A Marble Hornets Story was released; unlike Marble Hornets, critical reception to the film was predominantly negative.