Terrifier is a 2016 American slasher film written, edited, co-produced, and directed by Damien Leone. The film stars Jenna Kanell, Samantha Scaffidi, Catherine Corcoran, and David Howard Thornton. The plot centers on partygoer Tara Heyes (Kanell) and her sister Victoria (Scaffidi), who become targets of the enigmatic serial killer known only as Art the Clown (Thornton) on Halloween night.

Leone had created the character of Art the Clown for his short film The 9th Circle (2008) and then created another short with Terrifier (2011). These shorts would generate interest for what became the anthology film All Hallows' Eve (2013), which contained both segments. With the film, Leone wrote it specifically as a means of showcasing the character of Art and his practical effects work. Leone has since expressed regret for leaving the protagonists underdeveloped.

Leone tried to raise funds for the Terrifier feature film with an Indiegogo campaign, which fell short of its goal. However, producer Phil Falcone helped contribute funds to help make the film in exchange for a producer credit. Mike Giannelli, who portrayed prior incarnations of Art, retired from acting before production began, and David Howard Thornton replaced him as Art.

Terrifier premiered at the Telluride Horror Show on October 15, 2016, and received a limited theatrical release in the United States on March 15, 2018, by Epic Pictures Releasing. The film received generally mixed reviews from critics, with praise directed towards the special effects and the portrayals of Kanell, Scaffidi and Thornton, while the writing was subject to criticism. The film became a cult film, and would eventually generate a media franchise, with Terrifier 2, released on October 6, 2022 and Terrifier 3, released on October 11, 2024.