It, retroactively known as It Chapter One, is a 2017 supernatural horror film based on Stephen King's 1986 novel of the same name. Produced by New Line Cinema, KatzSmith Productions, Lin Pictures, Vertigo Entertainment, and distributed by Warner Bros.[5][6] It is the first film in the It film series as well as being the second adaptation following Tommy Lee Wallace's 1990 miniseries.[7][8][9] The film tells the story of seven children in Derry, Maine, who are terrorized by the eponymous being, only to face their own personal demons in the process. The film is also known as It: Part 1 – The Losers' Club.[N 1]

Directed by Andy Muschietti and written by Chase Palmer, Cary Fukunaga and Gary Dauberman, the film stars Jaeden Lieberher as Bill Denbrough, with Bill Skarsgård starring as Pennywise the Dancing Clown, respectively. Jeremy Ray Taylor, Sophia Lillis, Finn Wolfhard, Wyatt Oleff, Chosen Jacobs, Jack Dylan Grazer, Nicholas Hamilton, and Jackson Robert Scott are all featured in supporting roles. Principal photography began in Toronto on June 27, 2016, and ended on September 21, 2016. The locations for It were in the Greater Toronto Area, including Port Hope, Oshawa, and Riverdale.

It premiered in Los Angeles on September 5, 2017, and was released in the United States on September 8, 2017, in 2D and IMAX. The film set numerous box office records and grossed over $701 million worldwide, becoming the fifth-highest-grossing R-rated film of all time.[14] Unadjusted for inflation, it became the highest-grossing horror film of all time. It received positive reviews, with critics praising the performances, direction, cinematography and musical score, and many calling it one of the best Stephen King adaptations.[15] It has received numerous awards and nominations, earning two Washington D.C. Area Film Critics Association nominations, including Best Acting Ensemble. It was nominated for the Critics' Choice Movie Award for Best Sci-Fi/Horror Movie. The film won three Bogey Awards, for pulling in more than two million German admissions in 11 days.[16] In addition, the motion picture has been named as one of the best films of 2017 by various critics, appearing on several critics' end-of-year lists.[17] The sequel, It Chapter Two, was released on September 6, 2019.